diff --git a/protobuf/protobuf-core/src/commonMain/generated-code/kotlin-multiplatform/com/google/protobuf/kotlin/_rpc_internal/Any.kt b/protobuf/protobuf-core/src/commonMain/generated-code/kotlin-multiplatform/com/google/protobuf/kotlin/_rpc_internal/Any.kt
index 61f9897aa..f900fabf0 100644
--- a/protobuf/protobuf-core/src/commonMain/generated-code/kotlin-multiplatform/com/google/protobuf/kotlin/_rpc_internal/Any.kt
+++ b/protobuf/protobuf-core/src/commonMain/generated-code/kotlin-multiplatform/com/google/protobuf/kotlin/_rpc_internal/Any.kt
@@ -76,8 +76,12 @@ public fun com.google.protobuf.kotlin.AnyInternal.Companion.decodeWith(msg: com.
             }
 
             else -> { 
+                if (tag.wireType == kotlinx.rpc.protobuf.internal.WireType.END_GROUP) { 
+                    throw kotlinx.rpc.protobuf.internal.ProtobufDecodingException("Unexpected END_GROUP tag.")
+                }
+
                 // we are currently just skipping unknown fields (KRPC-191)
-                decoder.skipValue(tag.wireType)
+                decoder.skipValue(tag)
             }
         }
     }
diff --git a/protobuf/protobuf-core/src/commonMain/generated-code/kotlin-multiplatform/com/google/protobuf/kotlin/_rpc_internal/Api.kt b/protobuf/protobuf-core/src/commonMain/generated-code/kotlin-multiplatform/com/google/protobuf/kotlin/_rpc_internal/Api.kt
index 66760e11f..f1cc4a6b9 100644
--- a/protobuf/protobuf-core/src/commonMain/generated-code/kotlin-multiplatform/com/google/protobuf/kotlin/_rpc_internal/Api.kt
+++ b/protobuf/protobuf-core/src/commonMain/generated-code/kotlin-multiplatform/com/google/protobuf/kotlin/_rpc_internal/Api.kt
@@ -243,8 +243,12 @@ public fun com.google.protobuf.kotlin.ApiInternal.Companion.decodeWith(msg: com.
             }
 
             else -> { 
+                if (tag.wireType == kotlinx.rpc.protobuf.internal.WireType.END_GROUP) { 
+                    throw kotlinx.rpc.protobuf.internal.ProtobufDecodingException("Unexpected END_GROUP tag.")
+                }
+
                 // we are currently just skipping unknown fields (KRPC-191)
-                decoder.skipValue(tag.wireType)
+                decoder.skipValue(tag)
             }
         }
     }
@@ -365,8 +369,12 @@ public fun com.google.protobuf.kotlin.MethodInternal.Companion.decodeWith(msg: c
             }
 
             else -> { 
+                if (tag.wireType == kotlinx.rpc.protobuf.internal.WireType.END_GROUP) { 
+                    throw kotlinx.rpc.protobuf.internal.ProtobufDecodingException("Unexpected END_GROUP tag.")
+                }
+
                 // we are currently just skipping unknown fields (KRPC-191)
-                decoder.skipValue(tag.wireType)
+                decoder.skipValue(tag)
             }
         }
     }
@@ -440,8 +448,12 @@ public fun com.google.protobuf.kotlin.MixinInternal.Companion.decodeWith(msg: co
             }
 
             else -> { 
+                if (tag.wireType == kotlinx.rpc.protobuf.internal.WireType.END_GROUP) { 
+                    throw kotlinx.rpc.protobuf.internal.ProtobufDecodingException("Unexpected END_GROUP tag.")
+                }
+
                 // we are currently just skipping unknown fields (KRPC-191)
-                decoder.skipValue(tag.wireType)
+                decoder.skipValue(tag)
             }
         }
     }
diff --git a/protobuf/protobuf-core/src/commonMain/generated-code/kotlin-multiplatform/com/google/protobuf/kotlin/_rpc_internal/Duration.kt b/protobuf/protobuf-core/src/commonMain/generated-code/kotlin-multiplatform/com/google/protobuf/kotlin/_rpc_internal/Duration.kt
index a21fd44ae..11effb913 100644
--- a/protobuf/protobuf-core/src/commonMain/generated-code/kotlin-multiplatform/com/google/protobuf/kotlin/_rpc_internal/Duration.kt
+++ b/protobuf/protobuf-core/src/commonMain/generated-code/kotlin-multiplatform/com/google/protobuf/kotlin/_rpc_internal/Duration.kt
@@ -76,8 +76,12 @@ public fun com.google.protobuf.kotlin.DurationInternal.Companion.decodeWith(msg:
             }
 
             else -> { 
+                if (tag.wireType == kotlinx.rpc.protobuf.internal.WireType.END_GROUP) { 
+                    throw kotlinx.rpc.protobuf.internal.ProtobufDecodingException("Unexpected END_GROUP tag.")
+                }
+
                 // we are currently just skipping unknown fields (KRPC-191)
-                decoder.skipValue(tag.wireType)
+                decoder.skipValue(tag)
             }
         }
     }
diff --git a/protobuf/protobuf-core/src/commonMain/generated-code/kotlin-multiplatform/com/google/protobuf/kotlin/_rpc_internal/Empty.kt b/protobuf/protobuf-core/src/commonMain/generated-code/kotlin-multiplatform/com/google/protobuf/kotlin/_rpc_internal/Empty.kt
index 710388e37..9bb601255 100644
--- a/protobuf/protobuf-core/src/commonMain/generated-code/kotlin-multiplatform/com/google/protobuf/kotlin/_rpc_internal/Empty.kt
+++ b/protobuf/protobuf-core/src/commonMain/generated-code/kotlin-multiplatform/com/google/protobuf/kotlin/_rpc_internal/Empty.kt
@@ -59,8 +59,12 @@ public fun com.google.protobuf.kotlin.EmptyInternal.Companion.decodeWith(msg: co
         val tag = decoder.readTag() ?: break // EOF, we read the whole message
         when { 
             else -> { 
+                if (tag.wireType == kotlinx.rpc.protobuf.internal.WireType.END_GROUP) { 
+                    throw kotlinx.rpc.protobuf.internal.ProtobufDecodingException("Unexpected END_GROUP tag.")
+                }
+
                 // we are currently just skipping unknown fields (KRPC-191)
-                decoder.skipValue(tag.wireType)
+                decoder.skipValue(tag)
             }
         }
     }
diff --git a/protobuf/protobuf-core/src/commonMain/generated-code/kotlin-multiplatform/com/google/protobuf/kotlin/_rpc_internal/FieldMask.kt b/protobuf/protobuf-core/src/commonMain/generated-code/kotlin-multiplatform/com/google/protobuf/kotlin/_rpc_internal/FieldMask.kt
index da3284fca..b7e8411cb 100644
--- a/protobuf/protobuf-core/src/commonMain/generated-code/kotlin-multiplatform/com/google/protobuf/kotlin/_rpc_internal/FieldMask.kt
+++ b/protobuf/protobuf-core/src/commonMain/generated-code/kotlin-multiplatform/com/google/protobuf/kotlin/_rpc_internal/FieldMask.kt
@@ -70,8 +70,12 @@ public fun com.google.protobuf.kotlin.FieldMaskInternal.Companion.decodeWith(msg
             }
 
             else -> { 
+                if (tag.wireType == kotlinx.rpc.protobuf.internal.WireType.END_GROUP) { 
+                    throw kotlinx.rpc.protobuf.internal.ProtobufDecodingException("Unexpected END_GROUP tag.")
+                }
+
                 // we are currently just skipping unknown fields (KRPC-191)
-                decoder.skipValue(tag.wireType)
+                decoder.skipValue(tag)
             }
         }
     }
diff --git a/protobuf/protobuf-core/src/commonMain/generated-code/kotlin-multiplatform/com/google/protobuf/kotlin/_rpc_internal/SourceContext.kt b/protobuf/protobuf-core/src/commonMain/generated-code/kotlin-multiplatform/com/google/protobuf/kotlin/_rpc_internal/SourceContext.kt
index 4c79763a7..6b4c60a32 100644
--- a/protobuf/protobuf-core/src/commonMain/generated-code/kotlin-multiplatform/com/google/protobuf/kotlin/_rpc_internal/SourceContext.kt
+++ b/protobuf/protobuf-core/src/commonMain/generated-code/kotlin-multiplatform/com/google/protobuf/kotlin/_rpc_internal/SourceContext.kt
@@ -67,8 +67,12 @@ public fun com.google.protobuf.kotlin.SourceContextInternal.Companion.decodeWith
             }
 
             else -> { 
+                if (tag.wireType == kotlinx.rpc.protobuf.internal.WireType.END_GROUP) { 
+                    throw kotlinx.rpc.protobuf.internal.ProtobufDecodingException("Unexpected END_GROUP tag.")
+                }
+
                 // we are currently just skipping unknown fields (KRPC-191)
-                decoder.skipValue(tag.wireType)
+                decoder.skipValue(tag)
             }
         }
     }
diff --git a/protobuf/protobuf-core/src/commonMain/generated-code/kotlin-multiplatform/com/google/protobuf/kotlin/_rpc_internal/Struct.kt b/protobuf/protobuf-core/src/commonMain/generated-code/kotlin-multiplatform/com/google/protobuf/kotlin/_rpc_internal/Struct.kt
index 4f69c5022..a0cf20b59 100644
--- a/protobuf/protobuf-core/src/commonMain/generated-code/kotlin-multiplatform/com/google/protobuf/kotlin/_rpc_internal/Struct.kt
+++ b/protobuf/protobuf-core/src/commonMain/generated-code/kotlin-multiplatform/com/google/protobuf/kotlin/_rpc_internal/Struct.kt
@@ -176,8 +176,12 @@ public fun com.google.protobuf.kotlin.StructInternal.Companion.decodeWith(msg: c
             }
 
             else -> { 
+                if (tag.wireType == kotlinx.rpc.protobuf.internal.WireType.END_GROUP) { 
+                    throw kotlinx.rpc.protobuf.internal.ProtobufDecodingException("Unexpected END_GROUP tag.")
+                }
+
                 // we are currently just skipping unknown fields (KRPC-191)
-                decoder.skipValue(tag.wireType)
+                decoder.skipValue(tag)
             }
         }
     }
@@ -288,8 +292,12 @@ public fun com.google.protobuf.kotlin.ValueInternal.Companion.decodeWith(msg: co
             }
 
             else -> { 
+                if (tag.wireType == kotlinx.rpc.protobuf.internal.WireType.END_GROUP) { 
+                    throw kotlinx.rpc.protobuf.internal.ProtobufDecodingException("Unexpected END_GROUP tag.")
+                }
+
                 // we are currently just skipping unknown fields (KRPC-191)
-                decoder.skipValue(tag.wireType)
+                decoder.skipValue(tag)
             }
         }
     }
@@ -362,8 +370,12 @@ public fun com.google.protobuf.kotlin.ListValueInternal.Companion.decodeWith(msg
             }
 
             else -> { 
+                if (tag.wireType == kotlinx.rpc.protobuf.internal.WireType.END_GROUP) { 
+                    throw kotlinx.rpc.protobuf.internal.ProtobufDecodingException("Unexpected END_GROUP tag.")
+                }
+
                 // we are currently just skipping unknown fields (KRPC-191)
-                decoder.skipValue(tag.wireType)
+                decoder.skipValue(tag)
             }
         }
     }
@@ -420,8 +432,12 @@ public fun com.google.protobuf.kotlin.StructInternal.FieldsEntryInternal.Compani
             }
 
             else -> { 
+                if (tag.wireType == kotlinx.rpc.protobuf.internal.WireType.END_GROUP) { 
+                    throw kotlinx.rpc.protobuf.internal.ProtobufDecodingException("Unexpected END_GROUP tag.")
+                }
+
                 // we are currently just skipping unknown fields (KRPC-191)
-                decoder.skipValue(tag.wireType)
+                decoder.skipValue(tag)
             }
         }
     }
diff --git a/protobuf/protobuf-core/src/commonMain/generated-code/kotlin-multiplatform/com/google/protobuf/kotlin/_rpc_internal/Timestamp.kt b/protobuf/protobuf-core/src/commonMain/generated-code/kotlin-multiplatform/com/google/protobuf/kotlin/_rpc_internal/Timestamp.kt
index c3b2f51ea..1a78799e5 100644
--- a/protobuf/protobuf-core/src/commonMain/generated-code/kotlin-multiplatform/com/google/protobuf/kotlin/_rpc_internal/Timestamp.kt
+++ b/protobuf/protobuf-core/src/commonMain/generated-code/kotlin-multiplatform/com/google/protobuf/kotlin/_rpc_internal/Timestamp.kt
@@ -76,8 +76,12 @@ public fun com.google.protobuf.kotlin.TimestampInternal.Companion.decodeWith(msg
             }
 
             else -> { 
+                if (tag.wireType == kotlinx.rpc.protobuf.internal.WireType.END_GROUP) { 
+                    throw kotlinx.rpc.protobuf.internal.ProtobufDecodingException("Unexpected END_GROUP tag.")
+                }
+
                 // we are currently just skipping unknown fields (KRPC-191)
-                decoder.skipValue(tag.wireType)
+                decoder.skipValue(tag)
             }
         }
     }
diff --git a/protobuf/protobuf-core/src/commonMain/generated-code/kotlin-multiplatform/com/google/protobuf/kotlin/_rpc_internal/Type.kt b/protobuf/protobuf-core/src/commonMain/generated-code/kotlin-multiplatform/com/google/protobuf/kotlin/_rpc_internal/Type.kt
index 39e19e2d2..d688524dc 100644
--- a/protobuf/protobuf-core/src/commonMain/generated-code/kotlin-multiplatform/com/google/protobuf/kotlin/_rpc_internal/Type.kt
+++ b/protobuf/protobuf-core/src/commonMain/generated-code/kotlin-multiplatform/com/google/protobuf/kotlin/_rpc_internal/Type.kt
@@ -336,8 +336,12 @@ public fun com.google.protobuf.kotlin.TypeInternal.Companion.decodeWith(msg: com
             }
 
             else -> { 
+                if (tag.wireType == kotlinx.rpc.protobuf.internal.WireType.END_GROUP) { 
+                    throw kotlinx.rpc.protobuf.internal.ProtobufDecodingException("Unexpected END_GROUP tag.")
+                }
+
                 // we are currently just skipping unknown fields (KRPC-191)
-                decoder.skipValue(tag.wireType)
+                decoder.skipValue(tag)
             }
         }
     }
@@ -482,8 +486,12 @@ public fun com.google.protobuf.kotlin.FieldInternal.Companion.decodeWith(msg: co
             }
 
             else -> { 
+                if (tag.wireType == kotlinx.rpc.protobuf.internal.WireType.END_GROUP) { 
+                    throw kotlinx.rpc.protobuf.internal.ProtobufDecodingException("Unexpected END_GROUP tag.")
+                }
+
                 // we are currently just skipping unknown fields (KRPC-191)
-                decoder.skipValue(tag.wireType)
+                decoder.skipValue(tag)
             }
         }
     }
@@ -624,8 +632,12 @@ public fun com.google.protobuf.kotlin.EnumInternal.Companion.decodeWith(msg: com
             }
 
             else -> { 
+                if (tag.wireType == kotlinx.rpc.protobuf.internal.WireType.END_GROUP) { 
+                    throw kotlinx.rpc.protobuf.internal.ProtobufDecodingException("Unexpected END_GROUP tag.")
+                }
+
                 // we are currently just skipping unknown fields (KRPC-191)
-                decoder.skipValue(tag.wireType)
+                decoder.skipValue(tag)
             }
         }
     }
@@ -710,8 +722,12 @@ public fun com.google.protobuf.kotlin.EnumValueInternal.Companion.decodeWith(msg
             }
 
             else -> { 
+                if (tag.wireType == kotlinx.rpc.protobuf.internal.WireType.END_GROUP) { 
+                    throw kotlinx.rpc.protobuf.internal.ProtobufDecodingException("Unexpected END_GROUP tag.")
+                }
+
                 // we are currently just skipping unknown fields (KRPC-191)
-                decoder.skipValue(tag.wireType)
+                decoder.skipValue(tag)
             }
         }
     }
@@ -776,8 +792,12 @@ public fun com.google.protobuf.kotlin.OptionInternal.Companion.decodeWith(msg: c
             }
 
             else -> { 
+                if (tag.wireType == kotlinx.rpc.protobuf.internal.WireType.END_GROUP) { 
+                    throw kotlinx.rpc.protobuf.internal.ProtobufDecodingException("Unexpected END_GROUP tag.")
+                }
+
                 // we are currently just skipping unknown fields (KRPC-191)
-                decoder.skipValue(tag.wireType)
+                decoder.skipValue(tag)
             }
         }
     }
diff --git a/protobuf/protobuf-core/src/commonMain/generated-code/kotlin-multiplatform/com/google/protobuf/kotlin/_rpc_internal/Wrappers.kt b/protobuf/protobuf-core/src/commonMain/generated-code/kotlin-multiplatform/com/google/protobuf/kotlin/_rpc_internal/Wrappers.kt
index 19f862504..f50f6c53f 100644
--- a/protobuf/protobuf-core/src/commonMain/generated-code/kotlin-multiplatform/com/google/protobuf/kotlin/_rpc_internal/Wrappers.kt
+++ b/protobuf/protobuf-core/src/commonMain/generated-code/kotlin-multiplatform/com/google/protobuf/kotlin/_rpc_internal/Wrappers.kt
@@ -387,8 +387,12 @@ public fun com.google.protobuf.kotlin.DoubleValueInternal.Companion.decodeWith(m
             }
 
             else -> { 
+                if (tag.wireType == kotlinx.rpc.protobuf.internal.WireType.END_GROUP) { 
+                    throw kotlinx.rpc.protobuf.internal.ProtobufDecodingException("Unexpected END_GROUP tag.")
+                }
+
                 // we are currently just skipping unknown fields (KRPC-191)
-                decoder.skipValue(tag.wireType)
+                decoder.skipValue(tag)
             }
         }
     }
@@ -430,8 +434,12 @@ public fun com.google.protobuf.kotlin.FloatValueInternal.Companion.decodeWith(ms
             }
 
             else -> { 
+                if (tag.wireType == kotlinx.rpc.protobuf.internal.WireType.END_GROUP) { 
+                    throw kotlinx.rpc.protobuf.internal.ProtobufDecodingException("Unexpected END_GROUP tag.")
+                }
+
                 // we are currently just skipping unknown fields (KRPC-191)
-                decoder.skipValue(tag.wireType)
+                decoder.skipValue(tag)
             }
         }
     }
@@ -473,8 +481,12 @@ public fun com.google.protobuf.kotlin.Int64ValueInternal.Companion.decodeWith(ms
             }
 
             else -> { 
+                if (tag.wireType == kotlinx.rpc.protobuf.internal.WireType.END_GROUP) { 
+                    throw kotlinx.rpc.protobuf.internal.ProtobufDecodingException("Unexpected END_GROUP tag.")
+                }
+
                 // we are currently just skipping unknown fields (KRPC-191)
-                decoder.skipValue(tag.wireType)
+                decoder.skipValue(tag)
             }
         }
     }
@@ -516,8 +528,12 @@ public fun com.google.protobuf.kotlin.UInt64ValueInternal.Companion.decodeWith(m
             }
 
             else -> { 
+                if (tag.wireType == kotlinx.rpc.protobuf.internal.WireType.END_GROUP) { 
+                    throw kotlinx.rpc.protobuf.internal.ProtobufDecodingException("Unexpected END_GROUP tag.")
+                }
+
                 // we are currently just skipping unknown fields (KRPC-191)
-                decoder.skipValue(tag.wireType)
+                decoder.skipValue(tag)
             }
         }
     }
@@ -559,8 +575,12 @@ public fun com.google.protobuf.kotlin.Int32ValueInternal.Companion.decodeWith(ms
             }
 
             else -> { 
+                if (tag.wireType == kotlinx.rpc.protobuf.internal.WireType.END_GROUP) { 
+                    throw kotlinx.rpc.protobuf.internal.ProtobufDecodingException("Unexpected END_GROUP tag.")
+                }
+
                 // we are currently just skipping unknown fields (KRPC-191)
-                decoder.skipValue(tag.wireType)
+                decoder.skipValue(tag)
             }
         }
     }
@@ -602,8 +622,12 @@ public fun com.google.protobuf.kotlin.UInt32ValueInternal.Companion.decodeWith(m
             }
 
             else -> { 
+                if (tag.wireType == kotlinx.rpc.protobuf.internal.WireType.END_GROUP) { 
+                    throw kotlinx.rpc.protobuf.internal.ProtobufDecodingException("Unexpected END_GROUP tag.")
+                }
+
                 // we are currently just skipping unknown fields (KRPC-191)
-                decoder.skipValue(tag.wireType)
+                decoder.skipValue(tag)
             }
         }
     }
@@ -645,8 +669,12 @@ public fun com.google.protobuf.kotlin.BoolValueInternal.Companion.decodeWith(msg
             }
 
             else -> { 
+                if (tag.wireType == kotlinx.rpc.protobuf.internal.WireType.END_GROUP) { 
+                    throw kotlinx.rpc.protobuf.internal.ProtobufDecodingException("Unexpected END_GROUP tag.")
+                }
+
                 // we are currently just skipping unknown fields (KRPC-191)
-                decoder.skipValue(tag.wireType)
+                decoder.skipValue(tag)
             }
         }
     }
@@ -688,8 +716,12 @@ public fun com.google.protobuf.kotlin.StringValueInternal.Companion.decodeWith(m
             }
 
             else -> { 
+                if (tag.wireType == kotlinx.rpc.protobuf.internal.WireType.END_GROUP) { 
+                    throw kotlinx.rpc.protobuf.internal.ProtobufDecodingException("Unexpected END_GROUP tag.")
+                }
+
                 // we are currently just skipping unknown fields (KRPC-191)
-                decoder.skipValue(tag.wireType)
+                decoder.skipValue(tag)
             }
         }
     }
@@ -731,8 +763,12 @@ public fun com.google.protobuf.kotlin.BytesValueInternal.Companion.decodeWith(ms
             }
 
             else -> { 
+                if (tag.wireType == kotlinx.rpc.protobuf.internal.WireType.END_GROUP) { 
+                    throw kotlinx.rpc.protobuf.internal.ProtobufDecodingException("Unexpected END_GROUP tag.")
+                }
+
                 // we are currently just skipping unknown fields (KRPC-191)
-                decoder.skipValue(tag.wireType)
+                decoder.skipValue(tag)
             }
         }
     }
diff --git a/protobuf/protobuf-core/src/commonMain/kotlin/kotlinx/rpc/protobuf/internal/WireDecoder.kt b/protobuf/protobuf-core/src/commonMain/kotlin/kotlinx/rpc/protobuf/internal/WireDecoder.kt
index 79a3324d9..630c4dd82 100644
--- a/protobuf/protobuf-core/src/commonMain/kotlin/kotlinx/rpc/protobuf/internal/WireDecoder.kt
+++ b/protobuf/protobuf-core/src/commonMain/kotlin/kotlinx/rpc/protobuf/internal/WireDecoder.kt
@@ -91,16 +91,31 @@ public interface WireDecoder : AutoCloseable {
         popLimit(limit)
     }
 
-    public fun skipValue(writeType: WireType) {
-        when (writeType) {
+    public fun skipValue(tag: KTag) {
+        when (tag.wireType) {
             WireType.VARINT -> readInt64()
             WireType.FIXED32 -> readFixed32()
             WireType.FIXED64 -> readFixed64()
             WireType.LENGTH_DELIMITED -> readBytes()
-            WireType.START_GROUP -> throw ProtobufDecodingException("Unexpected START_GROUP wire type (KRPC-193)")
+            WireType.START_GROUP -> skipGroup(tag.fieldNr)
             WireType.END_GROUP -> {} // nothing to do
         }
     }
+
+    private fun skipGroup(startField: Int) {
+        // read until END_GROUP with the same field number
+        while (true) {
+            val t = readTag() ?: throw ProtobufDecodingException.truncatedMessage()
+            if (t.wireType == WireType.END_GROUP) {
+                if (t.fieldNr != startField) {
+                    throw ProtobufDecodingException("Mismatched END_GROUP: got ${t.fieldNr}, want $startField")
+                }
+                return
+            }
+            // recursively skip nested values (groups can nest)
+            skipValue(t)
+        }
+    }
 }
 
 /**
diff --git a/protobuf/protobuf-core/src/commonMain/kotlin/kotlinx/rpc/protobuf/internal/WireEncoder.kt b/protobuf/protobuf-core/src/commonMain/kotlin/kotlinx/rpc/protobuf/internal/WireEncoder.kt
index 856550539..d000fea08 100644
--- a/protobuf/protobuf-core/src/commonMain/kotlin/kotlinx/rpc/protobuf/internal/WireEncoder.kt
+++ b/protobuf/protobuf-core/src/commonMain/kotlin/kotlinx/rpc/protobuf/internal/WireEncoder.kt
@@ -60,6 +60,12 @@ public interface WireEncoder {
         encode: T.(WireEncoder) -> Unit,
     )
 
+    public fun <T : InternalMessage> writeGroupMessage(
+        fieldNr: Int,
+        value: T,
+        encode: T.(WireEncoder) -> Unit,
+    )
+
 }
 
 /**
diff --git a/protobuf/protobuf-core/src/commonTest/kotlin/kotlinx/rpc/protobuf/test/ProtosTest.kt b/protobuf/protobuf-core/src/commonTest/kotlin/kotlinx/rpc/protobuf/test/ProtosTest.kt
index 65338c867..0bb591c0b 100644
--- a/protobuf/protobuf-core/src/commonTest/kotlin/kotlinx/rpc/protobuf/test/ProtosTest.kt
+++ b/protobuf/protobuf-core/src/commonTest/kotlin/kotlinx/rpc/protobuf/test/ProtosTest.kt
@@ -18,16 +18,29 @@ import kotlinx.rpc.protobuf.input.stream.asInputStream
 import kotlinx.rpc.protobuf.input.stream.asSource
 import kotlinx.rpc.protobuf.internal.ProtobufDecodingException
 import kotlinx.rpc.protobuf.internal.WireEncoder
-import test.nested.*
+import test.groups.WithGroups
+import test.groups.WithGroupsInternal
+import test.groups.invoke
+import test.nested.NestedOuter
+import test.nested.NestedOuterInternal
+import test.nested.NotInside
+import test.nested.NotInsideInternal
 import test.nested.invoke
 import test.recursive.Recursive
 import test.recursive.RecursiveInternal
 import test.recursive.RecursiveReq
 import test.recursive.invoke
-import test.submsg.*
+import test.submsg.Other
+import test.submsg.OtherInternal
+import test.submsg.ReferenceInternal
+import test.submsg.encodeWith
 import test.submsg.invoke
-import kotlin.collections.iterator
-import kotlin.test.*
+import kotlin.test.Test
+import kotlin.test.assertEquals
+import kotlin.test.assertFailsWith
+import kotlin.test.assertIs
+import kotlin.test.assertNull
+import kotlin.test.assertTrue
 
 class ProtosTest {
 
@@ -411,4 +424,33 @@ class ProtosTest {
         }
     }
 
+    @Test
+    fun testGroup() {
+        val msg = WithGroups {
+            firstgroup = WithGroups.FirstGroup {
+                value = 23u
+            }
+            secondgroup = listOf(
+                WithGroups.SecondGroup {
+                    value = "First Item"
+                }, WithGroups.SecondGroup {
+                    value = "Second Item"
+                }
+            )
+            oneOfWithGroup = WithGroups.OneOfWithGroup.Testgroup(WithGroups.TestGroup {
+                value = 42u
+            })
+        }
+
+        val decoded = encodeDecode(msg, WithGroupsInternal.CODEC)
+        assertEquals(msg.firstgroup.value, decoded.firstgroup.value)
+        for ((i, group) in msg.secondgroup.withIndex()) {
+            assertEquals(group.value, decoded.secondgroup[i].value)
+        }
+        assertTrue(decoded.oneOfWithGroup is WithGroups.OneOfWithGroup.Testgroup)
+        assertEquals(
+            (msg.oneOfWithGroup as WithGroups.OneOfWithGroup.Testgroup).value.value,
+            (decoded.oneOfWithGroup as WithGroups.OneOfWithGroup.Testgroup).value.value
+        )
+    }
 }
diff --git a/protobuf/protobuf-core/src/commonTest/proto/groups.proto b/protobuf/protobuf-core/src/commonTest/proto/groups.proto
new file mode 100644
index 000000000..d092f40cc
--- /dev/null
+++ b/protobuf/protobuf-core/src/commonTest/proto/groups.proto
@@ -0,0 +1,18 @@
+package test.groups;
+
+message WithGroups {
+  required group FirstGroup = 1 {
+    required fixed32 value = 2;
+  }
+
+  repeated group SecondGroup = 2 {
+    required string value = 2;
+  }
+
+  oneof oneOfWithGroup {
+    int32 anInt32 = 4;
+    group TestGroup = 3 {
+      required fixed32 value = 2;
+    }
+  }
+}
\ No newline at end of file
diff --git a/protobuf/protobuf-core/src/jvmMain/kotlin/kotlinx/rpc/protobuf/internal/WireEncoder.jvm.kt b/protobuf/protobuf-core/src/jvmMain/kotlin/kotlinx/rpc/protobuf/internal/WireEncoder.jvm.kt
index 6054d5668..1bc1e78a9 100644
--- a/protobuf/protobuf-core/src/jvmMain/kotlin/kotlinx/rpc/protobuf/internal/WireEncoder.jvm.kt
+++ b/protobuf/protobuf-core/src/jvmMain/kotlin/kotlinx/rpc/protobuf/internal/WireEncoder.jvm.kt
@@ -182,6 +182,16 @@ private class WireEncoderJvm(sink: Sink) : WireEncoder {
         value.encode(this)
     }
 
+    override fun <T : InternalMessage> writeGroupMessage(
+        fieldNr: Int,
+        value: T,
+        encode: T.(WireEncoder) -> Unit,
+    ) {
+        codedOutputStream.writeTag(fieldNr, WireType.START_GROUP.ordinal)
+        value.encode(this)
+        codedOutputStream.writeTag(fieldNr, WireType.END_GROUP.ordinal)
+    }
+
     private inline fun <T> writePackedInternal(
         fieldNr: Int,
         value: List<T>,
diff --git a/protobuf/protobuf-core/src/nativeMain/kotlin/kotlinx/rpc/protobuf/internal/WireEncoder.native.kt b/protobuf/protobuf-core/src/nativeMain/kotlin/kotlinx/rpc/protobuf/internal/WireEncoder.native.kt
index b8171c74d..2cec9cfff 100644
--- a/protobuf/protobuf-core/src/nativeMain/kotlin/kotlinx/rpc/protobuf/internal/WireEncoder.native.kt
+++ b/protobuf/protobuf-core/src/nativeMain/kotlin/kotlinx/rpc/protobuf/internal/WireEncoder.native.kt
@@ -4,9 +4,53 @@
 
 package kotlinx.rpc.protobuf.internal
 
-import kotlinx.cinterop.*
+import kotlinx.cinterop.ByteVar
+import kotlinx.cinterop.CPointer
+import kotlinx.cinterop.CValuesRef
+import kotlinx.cinterop.ExperimentalForeignApi
+import kotlinx.cinterop.StableRef
+import kotlinx.cinterop.addressOf
+import kotlinx.cinterop.asStableRef
+import kotlinx.cinterop.cstr
+import kotlinx.cinterop.memScoped
+import kotlinx.cinterop.reinterpret
+import kotlinx.cinterop.staticCFunction
+import kotlinx.cinterop.usePinned
 import kotlinx.io.Sink
-import libprotowire.*
+import libprotowire.pw_encoder_delete
+import libprotowire.pw_encoder_flush
+import libprotowire.pw_encoder_new
+import libprotowire.pw_encoder_t
+import libprotowire.pw_encoder_write_bool
+import libprotowire.pw_encoder_write_bool_no_tag
+import libprotowire.pw_encoder_write_bytes
+import libprotowire.pw_encoder_write_double
+import libprotowire.pw_encoder_write_double_no_tag
+import libprotowire.pw_encoder_write_enum
+import libprotowire.pw_encoder_write_fixed32
+import libprotowire.pw_encoder_write_fixed32_no_tag
+import libprotowire.pw_encoder_write_fixed64
+import libprotowire.pw_encoder_write_fixed64_no_tag
+import libprotowire.pw_encoder_write_float
+import libprotowire.pw_encoder_write_float_no_tag
+import libprotowire.pw_encoder_write_int32
+import libprotowire.pw_encoder_write_int32_no_tag
+import libprotowire.pw_encoder_write_int64
+import libprotowire.pw_encoder_write_int64_no_tag
+import libprotowire.pw_encoder_write_sfixed32
+import libprotowire.pw_encoder_write_sfixed32_no_tag
+import libprotowire.pw_encoder_write_sfixed64
+import libprotowire.pw_encoder_write_sfixed64_no_tag
+import libprotowire.pw_encoder_write_sint32
+import libprotowire.pw_encoder_write_sint32_no_tag
+import libprotowire.pw_encoder_write_sint64
+import libprotowire.pw_encoder_write_sint64_no_tag
+import libprotowire.pw_encoder_write_string
+import libprotowire.pw_encoder_write_tag
+import libprotowire.pw_encoder_write_uint32
+import libprotowire.pw_encoder_write_uint32_no_tag
+import libprotowire.pw_encoder_write_uint64
+import libprotowire.pw_encoder_write_uint64_no_tag
 import kotlin.experimental.ExperimentalNativeApi
 import kotlin.native.ref.createCleaner
 
@@ -177,6 +221,12 @@ internal class WireEncoderNative(private val sink: Sink) : WireEncoder {
         pw_encoder_write_uint32_no_tag(raw, value._size.toUInt())
         value.encode(this)
     }
+
+    override fun <T : InternalMessage> writeGroupMessage(fieldNr: Int, value: T, encode: T.(WireEncoder) -> Unit) {
+        pw_encoder_write_tag(raw, fieldNr, WireType.START_GROUP.ordinal)
+        value.encode(this)
+        pw_encoder_write_tag(raw, fieldNr, WireType.END_GROUP.ordinal)
+    }
 }
 
 public actual fun WireEncoder(sink: Sink): WireEncoder = WireEncoderNative(sink)
diff --git a/protoc-gen/common/src/main/kotlin/kotlinx/rpc/protoc/gen/core/codeRequestToModel.kt b/protoc-gen/common/src/main/kotlin/kotlinx/rpc/protoc/gen/core/codeRequestToModel.kt
index 0cd5a1980..a40b3d191 100644
--- a/protoc-gen/common/src/main/kotlin/kotlinx/rpc/protoc/gen/core/codeRequestToModel.kt
+++ b/protoc-gen/common/src/main/kotlin/kotlinx/rpc/protoc/gen/core/codeRequestToModel.kt
@@ -7,7 +7,16 @@ package kotlinx.rpc.protoc.gen.core
 import com.google.protobuf.DescriptorProtos
 import com.google.protobuf.Descriptors
 import com.google.protobuf.compiler.PluginProtos.CodeGeneratorRequest
-import kotlinx.rpc.protoc.gen.core.model.*
+import kotlinx.rpc.protoc.gen.core.model.EnumDeclaration
+import kotlinx.rpc.protoc.gen.core.model.FieldDeclaration
+import kotlinx.rpc.protoc.gen.core.model.FieldType
+import kotlinx.rpc.protoc.gen.core.model.FileDeclaration
+import kotlinx.rpc.protoc.gen.core.model.FqName
+import kotlinx.rpc.protoc.gen.core.model.MessageDeclaration
+import kotlinx.rpc.protoc.gen.core.model.MethodDeclaration
+import kotlinx.rpc.protoc.gen.core.model.Model
+import kotlinx.rpc.protoc.gen.core.model.OneOfDeclaration
+import kotlinx.rpc.protoc.gen.core.model.ServiceDeclaration
 
 private val nameCache = mutableMapOf<Descriptors.GenericDescriptor, FqName>()
 private val modelCache = mutableMapOf<Descriptors.GenericDescriptor, Any>()
@@ -251,7 +260,7 @@ private fun Descriptors.FieldDescriptor.modelType(): FieldType {
         Descriptors.FieldDescriptor.Type.SINT64 -> FieldType.IntegralType.SINT64
         Descriptors.FieldDescriptor.Type.ENUM -> FieldType.Enum(enumType.toModel())
         Descriptors.FieldDescriptor.Type.MESSAGE -> FieldType.Message(lazy { messageType!!.toModel() })
-        Descriptors.FieldDescriptor.Type.GROUP -> error("GROUP type is unsupported")
+        Descriptors.FieldDescriptor.Type.GROUP -> FieldType.Message(lazy { messageType!!.toModel() })
     }
 
     if (isMapField) {
diff --git a/protoc-gen/common/src/main/kotlin/kotlinx/rpc/protoc/gen/core/model/FieldType.kt b/protoc-gen/common/src/main/kotlin/kotlinx/rpc/protoc/gen/core/model/FieldType.kt
index 2992e373c..541a959d2 100644
--- a/protoc-gen/common/src/main/kotlin/kotlinx/rpc/protoc/gen/core/model/FieldType.kt
+++ b/protoc-gen/common/src/main/kotlin/kotlinx/rpc/protoc/gen/core/model/FieldType.kt
@@ -40,7 +40,7 @@ sealed interface FieldType {
 
     data class Message(val dec: Lazy<MessageDeclaration>) : FieldType {
         override val defaultValue: String? = null
-        override val wireType: WireType = WireType.LENGTH_DELIMITED
+        override val wireType: WireType by lazy { if (dec.value.isGroup) WireType.START_GROUP else WireType.LENGTH_DELIMITED }
     }
 
     data class OneOf(val dec: OneOfDeclaration) : FieldType {
@@ -52,7 +52,7 @@ sealed interface FieldType {
         simpleName: String,
         override val defaultValue: String,
         override val wireType: WireType,
-        override val isPackable: Boolean = true
+        override val isPackable: Boolean = true,
     ) : FieldType {
         STRING("String", "\"\"", WireType.LENGTH_DELIMITED, false),
         BYTES("ByteArray", "byteArrayOf()", WireType.LENGTH_DELIMITED, false),
@@ -77,7 +77,7 @@ sealed interface FieldType {
 fun FieldType.scalarDefaultSuffix(): String = when (this) {
     FieldType.IntegralType.BOOL -> ""
     FieldType.IntegralType.FLOAT -> "f"
-    FieldType.IntegralType.DOUBLE ->  ""
+    FieldType.IntegralType.DOUBLE -> ""
     FieldType.IntegralType.INT32 -> ""
     FieldType.IntegralType.INT64 -> "L"
     FieldType.IntegralType.UINT32 -> "u"
diff --git a/protoc-gen/common/src/main/kotlin/kotlinx/rpc/protoc/gen/core/model/model.kt b/protoc-gen/common/src/main/kotlin/kotlinx/rpc/protoc/gen/core/model/model.kt
index 9077791ce..56c688f0f 100644
--- a/protoc-gen/common/src/main/kotlin/kotlinx/rpc/protoc/gen/core/model/model.kt
+++ b/protoc-gen/common/src/main/kotlin/kotlinx/rpc/protoc/gen/core/model/model.kt
@@ -33,6 +33,13 @@ data class MessageDeclaration(
 ) {
     val isMapEntry = dec.options.mapEntry
     val isUserFacing = !isMapEntry
+
+    val isGroup by lazy {
+        val parent = dec.containingType ?: return@lazy false // top-level types can’t be groups
+        parent.fields.any { f ->
+            f.type == Descriptors.FieldDescriptor.Type.GROUP && f.messageType == dec
+        }
+    }
 }
 
 data class EnumDeclaration(
@@ -68,7 +75,7 @@ data class EnumDeclaration(
 data class OneOfDeclaration(
     val name: FqName,
     val variants: List<FieldDeclaration>,
-    val dec: Descriptors.OneofDescriptor
+    val dec: Descriptors.OneofDescriptor,
 )
 
 data class FieldDeclaration(
@@ -78,9 +85,9 @@ data class FieldDeclaration(
     val dec: Descriptors.FieldDescriptor,
     // defines the index in the presenceMask of the Message.
     // this cannot be the number, as only fields with hasPresence == true are part of the presenceMask
-    val presenceIdx: Int? = null
+    val presenceIdx: Int? = null,
 ) {
-    val packedFixedSize = type.wireType == WireType.FIXED64 || type.wireType == WireType.FIXED32
+    val packedFixedSize by lazy { type.wireType == WireType.FIXED64 || type.wireType == WireType.FIXED32 }
 
     val isPartOfOneof: Boolean = dec.realContainingOneof != null
 
diff --git a/protoc-gen/protobuf/src/main/kotlin/kotlinx/rpc/protoc/gen/ModelToProtobufKotlinCommonGenerator.kt b/protoc-gen/protobuf/src/main/kotlin/kotlinx/rpc/protoc/gen/ModelToProtobufKotlinCommonGenerator.kt
index 96c3a9fbc..85920d03b 100644
--- a/protoc-gen/protobuf/src/main/kotlin/kotlinx/rpc/protoc/gen/ModelToProtobufKotlinCommonGenerator.kt
+++ b/protoc-gen/protobuf/src/main/kotlin/kotlinx/rpc/protoc/gen/ModelToProtobufKotlinCommonGenerator.kt
@@ -72,10 +72,15 @@ class ModelToProtobufKotlinCommonGenerator(
     private fun CodeGenerator.generatePublicMessage(declaration: MessageDeclaration) {
         if (!declaration.isUserFacing) return
 
+        val annotations = mutableListOf<String>()
+        if (!declaration.isGroup) {
+            annotations.add("@$WITH_CODEC_ANNO(${declaration.internalClassFullName()}.CODEC::class)")
+        }
+
         clazz(
             name = declaration.name.simpleName,
             declarationType = CodeGenerator.DeclarationType.Interface,
-            annotations = listOf("@$WITH_CODEC_ANNO(${declaration.internalClassFullName()}.CODEC::class)")
+            annotations = annotations
         ) {
             declaration.actualFields.forEachIndexed { i, field ->
                 property(
@@ -239,6 +244,8 @@ class ModelToProtobufKotlinCommonGenerator(
 
     private fun CodeGenerator.generateCodecObject(declaration: MessageDeclaration) {
         if (!declaration.isUserFacing) return
+        // the CODEC object is not necessary for groups, as they are inlined messages
+        if (declaration.isGroup) return
 
         val msgFqName = declaration.name.safeFullName()
         val inputStreamFqName = "kotlinx.rpc.protobuf.input.stream.InputStream"
@@ -291,25 +298,49 @@ class ModelToProtobufKotlinCommonGenerator(
         }
     }
 
-    private fun CodeGenerator.generateMessageDecoder(declaration: MessageDeclaration) = function(
-        name = "decodeWith",
-        args = "msg: ${declaration.internalClassFullName()}, decoder: $PB_PKG.WireDecoder",
-        annotations = listOf("@$INTERNAL_RPC_API_ANNO"),
-        contextReceiver = "${declaration.internalClassFullName()}.Companion",
-        returnType = "Unit",
-    ) {
-        whileBlock("true") {
-            code("val tag = decoder.readTag() ?: break // EOF, we read the whole message")
-            whenBlock {
-                declaration.actualFields.forEach { field -> readMatchCase(field) }
-                whenCase("else") {
-                    code("// we are currently just skipping unknown fields (KRPC-191)")
-                    code("decoder.skipValue(tag.wireType)")
+    private fun CodeGenerator.generateMessageDecoder(declaration: MessageDeclaration) {
+        var args = "msg: ${declaration.internalClassFullName()}, decoder: $PB_PKG.WireDecoder";
+        if (declaration.isGroup) {
+            args += ", startGroup: $PB_PKG.KTag"
+        }
+
+        function(
+            name = "decodeWith",
+            args = args,
+            annotations = listOf("@$INTERNAL_RPC_API_ANNO"),
+            contextReceiver = "${declaration.internalClassFullName()}.Companion",
+            returnType = "Unit",
+        ) {
+            whileBlock("true") {
+                if (declaration.isGroup) {
+                    code("val tag = decoder.readTag() ?: throw ProtobufDecodingException(\"Missing END_GROUP tag for field: \${startGroup.fieldNr}.\")")
+                    ifBranch(condition = "tag.wireType == $PB_PKG.WireType.END_GROUP", ifBlock = {
+                        ifBranch(condition = "tag.fieldNr != startGroup.fieldNr", ifBlock = {
+                            code("throw ProtobufDecodingException(\"Wrong END_GROUP tag. Expected \${startGroup.fieldNr}, got \${tag.fieldNr}.\")")
+                        })
+                        code("return")
+                    })
+                } else {
+                    code("val tag = decoder.readTag() ?: break // EOF, we read the whole message")
+                }
+
+                whenBlock {
+                    declaration.actualFields.forEach { field -> readMatchCase(field) }
+                    whenCase("else") {
+                        if (!declaration.isGroup) {
+                            // fail if we come across an END_GROUP in a normal message
+                            ifBranch(condition = "tag.wireType == $PB_PKG.WireType.END_GROUP", ifBlock = {
+                                code("throw $PB_PKG.ProtobufDecodingException(\"Unexpected END_GROUP tag.\")")
+                            })
+                        }
+                        code("// we are currently just skipping unknown fields (KRPC-191)")
+                        code("decoder.skipValue(tag)")
+                    }
                 }
             }
-        }
 
-        // TODO: Make lists and maps immutable (KRPC-190)
+            // TODO: Make lists and maps immutable (KRPC-190)
+        }
     }
 
     private fun CodeGenerator.readMatchCase(
@@ -374,7 +405,9 @@ class ModelToProtobufKotlinCommonGenerator(
             }
 
             is FieldType.Message -> {
-                whenCase("tag.fieldNr == ${field.number} && tag.wireType == $PB_PKG.WireType.LENGTH_DELIMITED") {
+                val msg = fieldType.dec.value
+
+                whenCase("tag.fieldNr == ${field.number} && tag.wireType == $PB_PKG.WireType.${fieldType.wireType.name}") {
                     if (field.presenceIdx != null) {
                         // check if the current sub message object was already set, if not, set a new one
                         // to set the field's presence tracker to true
@@ -448,8 +481,13 @@ class ModelToProtobufKotlinCommonGenerator(
             }
 
             is FieldType.Message -> {
-                val internalClassName = fieldType.dec.value.internalClassFullName()
-                code("decoder.readMessage($lvalue.asInternal(), $internalClassName::decodeWith)")
+                val msg = fieldType.dec.value
+                val fullClassName = msg.internalClassFullName()
+                if (msg.isGroup) {
+                    code("$fullClassName.decodeWith($lvalue.asInternal(), decoder, tag)")
+                } else {
+                    code("decoder.readMessage($lvalue.asInternal(), $fullClassName::decodeWith)")
+                }
             }
 
             is FieldType.Map -> {
@@ -527,7 +565,8 @@ class ModelToProtobufKotlinCommonGenerator(
                     valueVar
                 }
 
-                encFunc = type.value.decodeEncodeFuncName()
+                val innerType = type.value
+                encFunc = innerType.decodeEncodeFuncName()
                 when {
                     isPacked && packedWithFixedSize ->
                         code("encoder.writePacked${encFunc!!}(fieldNr = $number, value = $packedValueVar)")
@@ -539,8 +578,8 @@ class ModelToProtobufKotlinCommonGenerator(
                             })"
                         )
 
-                    type.value is FieldType.Message -> scope("$valueVar.forEach") {
-                        code("encoder.writeMessage(fieldNr = ${number}, value = it.asInternal()) { encodeWith(it) }")
+                    innerType is FieldType.Message -> scope("$valueVar.forEach") {
+                        generateEncodeFieldValue("it", innerType, number, isPacked = false, packedWithFixedSize = false)
                     }
 
                     else -> {
@@ -578,7 +617,10 @@ class ModelToProtobufKotlinCommonGenerator(
                 }
             }
 
-            is FieldType.Message -> code("encoder.writeMessage(fieldNr = ${number}, value = $valueVar.asInternal()) { encodeWith(it) }")
+            is FieldType.Message -> {
+                val writeMethod = if (type.dec.value.isGroup) "writeGroupMessage" else "writeMessage"
+                code("encoder.$writeMethod(fieldNr = ${number}, value = $valueVar.asInternal()) { encodeWith(it) }")
+            }
         }
 
     }
@@ -729,14 +771,21 @@ class ModelToProtobufKotlinCommonGenerator(
         val valueSize by lazy { field.type.valueSizeCall(variable, field.number, field.dec.isPacked) }
         val tagSize = tagSizeCall(field.number, field.type.wireType)
 
-        when (field.type) {
+        when (val fieldType = field.type) {
             is FieldType.List -> when {
                 // packed fields also have the tag + len
                 field.dec.isPacked -> code("__result += $valueSize.let { $tagSize + ${int32SizeCall("it")} + it }")
                 else -> code("__result += $valueSize")
             }
 
-            is FieldType.Message,
+            is FieldType.Message -> if (fieldType.dec.value.isGroup) {
+                val groupTagSize = tagSizeCall(field.number, WireType.START_GROUP)
+                // the group message size is the size of the message plus the start and end group tags
+                code("__result += $valueSize.let { (2 * $groupTagSize) + it }")
+            } else {
+                code("__result += $valueSize.let { $tagSize + ${int32SizeCall("it")} + it }")
+            }
+
             FieldType.IntegralType.STRING,
             FieldType.IntegralType.BYTES,
                 -> code("__result += $valueSize.let { $tagSize + ${int32SizeCall("it")} + it }")
diff --git a/.setup_protoscope.sh b/setup_protocscope.sh
old mode 100644
new mode 100755
similarity index 100%
rename from .setup_protoscope.sh
rename to setup_protocscope.sh
diff --git a/tests/protobuf-conformance/src/main/generated-code/kotlin-multiplatform/com/google/protobuf/conformance/_rpc_internal/Conformance.kt b/tests/protobuf-conformance/src/main/generated-code/kotlin-multiplatform/com/google/protobuf/conformance/_rpc_internal/Conformance.kt
index 16a272564..0756143b7 100644
--- a/tests/protobuf-conformance/src/main/generated-code/kotlin-multiplatform/com/google/protobuf/conformance/_rpc_internal/Conformance.kt
+++ b/tests/protobuf-conformance/src/main/generated-code/kotlin-multiplatform/com/google/protobuf/conformance/_rpc_internal/Conformance.kt
@@ -254,8 +254,12 @@ fun com.google.protobuf.conformance.TestStatusInternal.Companion.decodeWith(msg:
             }
 
             else -> { 
+                if (tag.wireType == kotlinx.rpc.protobuf.internal.WireType.END_GROUP) { 
+                    throw kotlinx.rpc.protobuf.internal.ProtobufDecodingException("Unexpected END_GROUP tag.")
+                }
+
                 // we are currently just skipping unknown fields (KRPC-191)
-                decoder.skipValue(tag.wireType)
+                decoder.skipValue(tag)
             }
         }
     }
@@ -312,8 +316,12 @@ fun com.google.protobuf.conformance.FailureSetInternal.Companion.decodeWith(msg:
             }
 
             else -> { 
+                if (tag.wireType == kotlinx.rpc.protobuf.internal.WireType.END_GROUP) { 
+                    throw kotlinx.rpc.protobuf.internal.ProtobufDecodingException("Unexpected END_GROUP tag.")
+                }
+
                 // we are currently just skipping unknown fields (KRPC-191)
-                decoder.skipValue(tag.wireType)
+                decoder.skipValue(tag)
             }
         }
     }
@@ -430,8 +438,12 @@ fun com.google.protobuf.conformance.ConformanceRequestInternal.Companion.decodeW
             }
 
             else -> { 
+                if (tag.wireType == kotlinx.rpc.protobuf.internal.WireType.END_GROUP) { 
+                    throw kotlinx.rpc.protobuf.internal.ProtobufDecodingException("Unexpected END_GROUP tag.")
+                }
+
                 // we are currently just skipping unknown fields (KRPC-191)
-                decoder.skipValue(tag.wireType)
+                decoder.skipValue(tag)
             }
         }
     }
@@ -577,8 +589,12 @@ fun com.google.protobuf.conformance.ConformanceResponseInternal.Companion.decode
             }
 
             else -> { 
+                if (tag.wireType == kotlinx.rpc.protobuf.internal.WireType.END_GROUP) { 
+                    throw kotlinx.rpc.protobuf.internal.ProtobufDecodingException("Unexpected END_GROUP tag.")
+                }
+
                 // we are currently just skipping unknown fields (KRPC-191)
-                decoder.skipValue(tag.wireType)
+                decoder.skipValue(tag)
             }
         }
     }
@@ -656,8 +672,12 @@ fun com.google.protobuf.conformance.JspbEncodingConfigInternal.Companion.decodeW
             }
 
             else -> { 
+                if (tag.wireType == kotlinx.rpc.protobuf.internal.WireType.END_GROUP) { 
+                    throw kotlinx.rpc.protobuf.internal.ProtobufDecodingException("Unexpected END_GROUP tag.")
+                }
+
                 // we are currently just skipping unknown fields (KRPC-191)
-                decoder.skipValue(tag.wireType)
+                decoder.skipValue(tag)
             }
         }
     }
diff --git a/tests/protobuf-conformance/src/main/generated-code/kotlin-multiplatform/com/google/protobuf_test_messages/editions/proto3/_rpc_internal/TestMessagesProto3Editions.kt b/tests/protobuf-conformance/src/main/generated-code/kotlin-multiplatform/com/google/protobuf_test_messages/editions/proto3/_rpc_internal/TestMessagesProto3Editions.kt
index 2ccd5e011..fb1f82144 100644
--- a/tests/protobuf-conformance/src/main/generated-code/kotlin-multiplatform/com/google/protobuf_test_messages/editions/proto3/_rpc_internal/TestMessagesProto3Editions.kt
+++ b/tests/protobuf-conformance/src/main/generated-code/kotlin-multiplatform/com/google/protobuf_test_messages/editions/proto3/_rpc_internal/TestMessagesProto3Editions.kt
@@ -2583,8 +2583,12 @@ fun com.google.protobuf_test_messages.editions.proto3.TestAllTypesProto3Internal
             }
 
             else -> { 
+                if (tag.wireType == kotlinx.rpc.protobuf.internal.WireType.END_GROUP) { 
+                    throw kotlinx.rpc.protobuf.internal.ProtobufDecodingException("Unexpected END_GROUP tag.")
+                }
+
                 // we are currently just skipping unknown fields (KRPC-191)
-                decoder.skipValue(tag.wireType)
+                decoder.skipValue(tag)
             }
         }
     }
@@ -3344,8 +3348,12 @@ fun com.google.protobuf_test_messages.editions.proto3.ForeignMessageInternal.Com
             }
 
             else -> { 
+                if (tag.wireType == kotlinx.rpc.protobuf.internal.WireType.END_GROUP) { 
+                    throw kotlinx.rpc.protobuf.internal.ProtobufDecodingException("Unexpected END_GROUP tag.")
+                }
+
                 // we are currently just skipping unknown fields (KRPC-191)
-                decoder.skipValue(tag.wireType)
+                decoder.skipValue(tag)
             }
         }
     }
@@ -3381,8 +3389,12 @@ fun com.google.protobuf_test_messages.editions.proto3.NullHypothesisProto3Intern
         val tag = decoder.readTag() ?: break // EOF, we read the whole message
         when { 
             else -> { 
+                if (tag.wireType == kotlinx.rpc.protobuf.internal.WireType.END_GROUP) { 
+                    throw kotlinx.rpc.protobuf.internal.ProtobufDecodingException("Unexpected END_GROUP tag.")
+                }
+
                 // we are currently just skipping unknown fields (KRPC-191)
-                decoder.skipValue(tag.wireType)
+                decoder.skipValue(tag)
             }
         }
     }
@@ -3414,8 +3426,12 @@ fun com.google.protobuf_test_messages.editions.proto3.EnumOnlyProto3Internal.Com
         val tag = decoder.readTag() ?: break // EOF, we read the whole message
         when { 
             else -> { 
+                if (tag.wireType == kotlinx.rpc.protobuf.internal.WireType.END_GROUP) { 
+                    throw kotlinx.rpc.protobuf.internal.ProtobufDecodingException("Unexpected END_GROUP tag.")
+                }
+
                 // we are currently just skipping unknown fields (KRPC-191)
-                decoder.skipValue(tag.wireType)
+                decoder.skipValue(tag)
             }
         }
     }
@@ -3468,8 +3484,12 @@ fun com.google.protobuf_test_messages.editions.proto3.TestAllTypesProto3Internal
             }
 
             else -> { 
+                if (tag.wireType == kotlinx.rpc.protobuf.internal.WireType.END_GROUP) { 
+                    throw kotlinx.rpc.protobuf.internal.ProtobufDecodingException("Unexpected END_GROUP tag.")
+                }
+
                 // we are currently just skipping unknown fields (KRPC-191)
-                decoder.skipValue(tag.wireType)
+                decoder.skipValue(tag)
             }
         }
     }
@@ -3523,8 +3543,12 @@ fun com.google.protobuf_test_messages.editions.proto3.TestAllTypesProto3Internal
             }
 
             else -> { 
+                if (tag.wireType == kotlinx.rpc.protobuf.internal.WireType.END_GROUP) { 
+                    throw kotlinx.rpc.protobuf.internal.ProtobufDecodingException("Unexpected END_GROUP tag.")
+                }
+
                 // we are currently just skipping unknown fields (KRPC-191)
-                decoder.skipValue(tag.wireType)
+                decoder.skipValue(tag)
             }
         }
     }
@@ -3578,8 +3602,12 @@ fun com.google.protobuf_test_messages.editions.proto3.TestAllTypesProto3Internal
             }
 
             else -> { 
+                if (tag.wireType == kotlinx.rpc.protobuf.internal.WireType.END_GROUP) { 
+                    throw kotlinx.rpc.protobuf.internal.ProtobufDecodingException("Unexpected END_GROUP tag.")
+                }
+
                 // we are currently just skipping unknown fields (KRPC-191)
-                decoder.skipValue(tag.wireType)
+                decoder.skipValue(tag)
             }
         }
     }
@@ -3633,8 +3661,12 @@ fun com.google.protobuf_test_messages.editions.proto3.TestAllTypesProto3Internal
             }
 
             else -> { 
+                if (tag.wireType == kotlinx.rpc.protobuf.internal.WireType.END_GROUP) { 
+                    throw kotlinx.rpc.protobuf.internal.ProtobufDecodingException("Unexpected END_GROUP tag.")
+                }
+
                 // we are currently just skipping unknown fields (KRPC-191)
-                decoder.skipValue(tag.wireType)
+                decoder.skipValue(tag)
             }
         }
     }
@@ -3688,8 +3720,12 @@ fun com.google.protobuf_test_messages.editions.proto3.TestAllTypesProto3Internal
             }
 
             else -> { 
+                if (tag.wireType == kotlinx.rpc.protobuf.internal.WireType.END_GROUP) { 
+                    throw kotlinx.rpc.protobuf.internal.ProtobufDecodingException("Unexpected END_GROUP tag.")
+                }
+
                 // we are currently just skipping unknown fields (KRPC-191)
-                decoder.skipValue(tag.wireType)
+                decoder.skipValue(tag)
             }
         }
     }
@@ -3743,8 +3779,12 @@ fun com.google.protobuf_test_messages.editions.proto3.TestAllTypesProto3Internal
             }
 
             else -> { 
+                if (tag.wireType == kotlinx.rpc.protobuf.internal.WireType.END_GROUP) { 
+                    throw kotlinx.rpc.protobuf.internal.ProtobufDecodingException("Unexpected END_GROUP tag.")
+                }
+
                 // we are currently just skipping unknown fields (KRPC-191)
-                decoder.skipValue(tag.wireType)
+                decoder.skipValue(tag)
             }
         }
     }
@@ -3798,8 +3838,12 @@ fun com.google.protobuf_test_messages.editions.proto3.TestAllTypesProto3Internal
             }
 
             else -> { 
+                if (tag.wireType == kotlinx.rpc.protobuf.internal.WireType.END_GROUP) { 
+                    throw kotlinx.rpc.protobuf.internal.ProtobufDecodingException("Unexpected END_GROUP tag.")
+                }
+
                 // we are currently just skipping unknown fields (KRPC-191)
-                decoder.skipValue(tag.wireType)
+                decoder.skipValue(tag)
             }
         }
     }
@@ -3853,8 +3897,12 @@ fun com.google.protobuf_test_messages.editions.proto3.TestAllTypesProto3Internal
             }
 
             else -> { 
+                if (tag.wireType == kotlinx.rpc.protobuf.internal.WireType.END_GROUP) { 
+                    throw kotlinx.rpc.protobuf.internal.ProtobufDecodingException("Unexpected END_GROUP tag.")
+                }
+
                 // we are currently just skipping unknown fields (KRPC-191)
-                decoder.skipValue(tag.wireType)
+                decoder.skipValue(tag)
             }
         }
     }
@@ -3908,8 +3956,12 @@ fun com.google.protobuf_test_messages.editions.proto3.TestAllTypesProto3Internal
             }
 
             else -> { 
+                if (tag.wireType == kotlinx.rpc.protobuf.internal.WireType.END_GROUP) { 
+                    throw kotlinx.rpc.protobuf.internal.ProtobufDecodingException("Unexpected END_GROUP tag.")
+                }
+
                 // we are currently just skipping unknown fields (KRPC-191)
-                decoder.skipValue(tag.wireType)
+                decoder.skipValue(tag)
             }
         }
     }
@@ -3963,8 +4015,12 @@ fun com.google.protobuf_test_messages.editions.proto3.TestAllTypesProto3Internal
             }
 
             else -> { 
+                if (tag.wireType == kotlinx.rpc.protobuf.internal.WireType.END_GROUP) { 
+                    throw kotlinx.rpc.protobuf.internal.ProtobufDecodingException("Unexpected END_GROUP tag.")
+                }
+
                 // we are currently just skipping unknown fields (KRPC-191)
-                decoder.skipValue(tag.wireType)
+                decoder.skipValue(tag)
             }
         }
     }
@@ -4018,8 +4074,12 @@ fun com.google.protobuf_test_messages.editions.proto3.TestAllTypesProto3Internal
             }
 
             else -> { 
+                if (tag.wireType == kotlinx.rpc.protobuf.internal.WireType.END_GROUP) { 
+                    throw kotlinx.rpc.protobuf.internal.ProtobufDecodingException("Unexpected END_GROUP tag.")
+                }
+
                 // we are currently just skipping unknown fields (KRPC-191)
-                decoder.skipValue(tag.wireType)
+                decoder.skipValue(tag)
             }
         }
     }
@@ -4073,8 +4133,12 @@ fun com.google.protobuf_test_messages.editions.proto3.TestAllTypesProto3Internal
             }
 
             else -> { 
+                if (tag.wireType == kotlinx.rpc.protobuf.internal.WireType.END_GROUP) { 
+                    throw kotlinx.rpc.protobuf.internal.ProtobufDecodingException("Unexpected END_GROUP tag.")
+                }
+
                 // we are currently just skipping unknown fields (KRPC-191)
-                decoder.skipValue(tag.wireType)
+                decoder.skipValue(tag)
             }
         }
     }
@@ -4128,8 +4192,12 @@ fun com.google.protobuf_test_messages.editions.proto3.TestAllTypesProto3Internal
             }
 
             else -> { 
+                if (tag.wireType == kotlinx.rpc.protobuf.internal.WireType.END_GROUP) { 
+                    throw kotlinx.rpc.protobuf.internal.ProtobufDecodingException("Unexpected END_GROUP tag.")
+                }
+
                 // we are currently just skipping unknown fields (KRPC-191)
-                decoder.skipValue(tag.wireType)
+                decoder.skipValue(tag)
             }
         }
     }
@@ -4183,8 +4251,12 @@ fun com.google.protobuf_test_messages.editions.proto3.TestAllTypesProto3Internal
             }
 
             else -> { 
+                if (tag.wireType == kotlinx.rpc.protobuf.internal.WireType.END_GROUP) { 
+                    throw kotlinx.rpc.protobuf.internal.ProtobufDecodingException("Unexpected END_GROUP tag.")
+                }
+
                 // we are currently just skipping unknown fields (KRPC-191)
-                decoder.skipValue(tag.wireType)
+                decoder.skipValue(tag)
             }
         }
     }
@@ -4238,8 +4310,12 @@ fun com.google.protobuf_test_messages.editions.proto3.TestAllTypesProto3Internal
             }
 
             else -> { 
+                if (tag.wireType == kotlinx.rpc.protobuf.internal.WireType.END_GROUP) { 
+                    throw kotlinx.rpc.protobuf.internal.ProtobufDecodingException("Unexpected END_GROUP tag.")
+                }
+
                 // we are currently just skipping unknown fields (KRPC-191)
-                decoder.skipValue(tag.wireType)
+                decoder.skipValue(tag)
             }
         }
     }
@@ -4293,8 +4369,12 @@ fun com.google.protobuf_test_messages.editions.proto3.TestAllTypesProto3Internal
             }
 
             else -> { 
+                if (tag.wireType == kotlinx.rpc.protobuf.internal.WireType.END_GROUP) { 
+                    throw kotlinx.rpc.protobuf.internal.ProtobufDecodingException("Unexpected END_GROUP tag.")
+                }
+
                 // we are currently just skipping unknown fields (KRPC-191)
-                decoder.skipValue(tag.wireType)
+                decoder.skipValue(tag)
             }
         }
     }
@@ -4355,8 +4435,12 @@ fun com.google.protobuf_test_messages.editions.proto3.TestAllTypesProto3Internal
             }
 
             else -> { 
+                if (tag.wireType == kotlinx.rpc.protobuf.internal.WireType.END_GROUP) { 
+                    throw kotlinx.rpc.protobuf.internal.ProtobufDecodingException("Unexpected END_GROUP tag.")
+                }
+
                 // we are currently just skipping unknown fields (KRPC-191)
-                decoder.skipValue(tag.wireType)
+                decoder.skipValue(tag)
             }
         }
     }
@@ -4417,8 +4501,12 @@ fun com.google.protobuf_test_messages.editions.proto3.TestAllTypesProto3Internal
             }
 
             else -> { 
+                if (tag.wireType == kotlinx.rpc.protobuf.internal.WireType.END_GROUP) { 
+                    throw kotlinx.rpc.protobuf.internal.ProtobufDecodingException("Unexpected END_GROUP tag.")
+                }
+
                 // we are currently just skipping unknown fields (KRPC-191)
-                decoder.skipValue(tag.wireType)
+                decoder.skipValue(tag)
             }
         }
     }
@@ -4472,8 +4560,12 @@ fun com.google.protobuf_test_messages.editions.proto3.TestAllTypesProto3Internal
             }
 
             else -> { 
+                if (tag.wireType == kotlinx.rpc.protobuf.internal.WireType.END_GROUP) { 
+                    throw kotlinx.rpc.protobuf.internal.ProtobufDecodingException("Unexpected END_GROUP tag.")
+                }
+
                 // we are currently just skipping unknown fields (KRPC-191)
-                decoder.skipValue(tag.wireType)
+                decoder.skipValue(tag)
             }
         }
     }
@@ -4527,8 +4619,12 @@ fun com.google.protobuf_test_messages.editions.proto3.TestAllTypesProto3Internal
             }
 
             else -> { 
+                if (tag.wireType == kotlinx.rpc.protobuf.internal.WireType.END_GROUP) { 
+                    throw kotlinx.rpc.protobuf.internal.ProtobufDecodingException("Unexpected END_GROUP tag.")
+                }
+
                 // we are currently just skipping unknown fields (KRPC-191)
-                decoder.skipValue(tag.wireType)
+                decoder.skipValue(tag)
             }
         }
     }
diff --git a/tests/protobuf-conformance/src/main/generated-code/kotlin-multiplatform/com/google/protobuf_test_messages/proto3/_rpc_internal/TestMessagesProto3.kt b/tests/protobuf-conformance/src/main/generated-code/kotlin-multiplatform/com/google/protobuf_test_messages/proto3/_rpc_internal/TestMessagesProto3.kt
index df9366597..3def5c591 100644
--- a/tests/protobuf-conformance/src/main/generated-code/kotlin-multiplatform/com/google/protobuf_test_messages/proto3/_rpc_internal/TestMessagesProto3.kt
+++ b/tests/protobuf-conformance/src/main/generated-code/kotlin-multiplatform/com/google/protobuf_test_messages/proto3/_rpc_internal/TestMessagesProto3.kt
@@ -2583,8 +2583,12 @@ fun com.google.protobuf_test_messages.proto3.TestAllTypesProto3Internal.Companio
             }
 
             else -> { 
+                if (tag.wireType == kotlinx.rpc.protobuf.internal.WireType.END_GROUP) { 
+                    throw kotlinx.rpc.protobuf.internal.ProtobufDecodingException("Unexpected END_GROUP tag.")
+                }
+
                 // we are currently just skipping unknown fields (KRPC-191)
-                decoder.skipValue(tag.wireType)
+                decoder.skipValue(tag)
             }
         }
     }
@@ -3344,8 +3348,12 @@ fun com.google.protobuf_test_messages.proto3.ForeignMessageInternal.Companion.de
             }
 
             else -> { 
+                if (tag.wireType == kotlinx.rpc.protobuf.internal.WireType.END_GROUP) { 
+                    throw kotlinx.rpc.protobuf.internal.ProtobufDecodingException("Unexpected END_GROUP tag.")
+                }
+
                 // we are currently just skipping unknown fields (KRPC-191)
-                decoder.skipValue(tag.wireType)
+                decoder.skipValue(tag)
             }
         }
     }
@@ -3381,8 +3389,12 @@ fun com.google.protobuf_test_messages.proto3.NullHypothesisProto3Internal.Compan
         val tag = decoder.readTag() ?: break // EOF, we read the whole message
         when { 
             else -> { 
+                if (tag.wireType == kotlinx.rpc.protobuf.internal.WireType.END_GROUP) { 
+                    throw kotlinx.rpc.protobuf.internal.ProtobufDecodingException("Unexpected END_GROUP tag.")
+                }
+
                 // we are currently just skipping unknown fields (KRPC-191)
-                decoder.skipValue(tag.wireType)
+                decoder.skipValue(tag)
             }
         }
     }
@@ -3414,8 +3426,12 @@ fun com.google.protobuf_test_messages.proto3.EnumOnlyProto3Internal.Companion.de
         val tag = decoder.readTag() ?: break // EOF, we read the whole message
         when { 
             else -> { 
+                if (tag.wireType == kotlinx.rpc.protobuf.internal.WireType.END_GROUP) { 
+                    throw kotlinx.rpc.protobuf.internal.ProtobufDecodingException("Unexpected END_GROUP tag.")
+                }
+
                 // we are currently just skipping unknown fields (KRPC-191)
-                decoder.skipValue(tag.wireType)
+                decoder.skipValue(tag)
             }
         }
     }
@@ -3468,8 +3484,12 @@ fun com.google.protobuf_test_messages.proto3.TestAllTypesProto3Internal.NestedMe
             }
 
             else -> { 
+                if (tag.wireType == kotlinx.rpc.protobuf.internal.WireType.END_GROUP) { 
+                    throw kotlinx.rpc.protobuf.internal.ProtobufDecodingException("Unexpected END_GROUP tag.")
+                }
+
                 // we are currently just skipping unknown fields (KRPC-191)
-                decoder.skipValue(tag.wireType)
+                decoder.skipValue(tag)
             }
         }
     }
@@ -3523,8 +3543,12 @@ fun com.google.protobuf_test_messages.proto3.TestAllTypesProto3Internal.MapInt32
             }
 
             else -> { 
+                if (tag.wireType == kotlinx.rpc.protobuf.internal.WireType.END_GROUP) { 
+                    throw kotlinx.rpc.protobuf.internal.ProtobufDecodingException("Unexpected END_GROUP tag.")
+                }
+
                 // we are currently just skipping unknown fields (KRPC-191)
-                decoder.skipValue(tag.wireType)
+                decoder.skipValue(tag)
             }
         }
     }
@@ -3578,8 +3602,12 @@ fun com.google.protobuf_test_messages.proto3.TestAllTypesProto3Internal.MapInt64
             }
 
             else -> { 
+                if (tag.wireType == kotlinx.rpc.protobuf.internal.WireType.END_GROUP) { 
+                    throw kotlinx.rpc.protobuf.internal.ProtobufDecodingException("Unexpected END_GROUP tag.")
+                }
+
                 // we are currently just skipping unknown fields (KRPC-191)
-                decoder.skipValue(tag.wireType)
+                decoder.skipValue(tag)
             }
         }
     }
@@ -3633,8 +3661,12 @@ fun com.google.protobuf_test_messages.proto3.TestAllTypesProto3Internal.MapUint3
             }
 
             else -> { 
+                if (tag.wireType == kotlinx.rpc.protobuf.internal.WireType.END_GROUP) { 
+                    throw kotlinx.rpc.protobuf.internal.ProtobufDecodingException("Unexpected END_GROUP tag.")
+                }
+
                 // we are currently just skipping unknown fields (KRPC-191)
-                decoder.skipValue(tag.wireType)
+                decoder.skipValue(tag)
             }
         }
     }
@@ -3688,8 +3720,12 @@ fun com.google.protobuf_test_messages.proto3.TestAllTypesProto3Internal.MapUint6
             }
 
             else -> { 
+                if (tag.wireType == kotlinx.rpc.protobuf.internal.WireType.END_GROUP) { 
+                    throw kotlinx.rpc.protobuf.internal.ProtobufDecodingException("Unexpected END_GROUP tag.")
+                }
+
                 // we are currently just skipping unknown fields (KRPC-191)
-                decoder.skipValue(tag.wireType)
+                decoder.skipValue(tag)
             }
         }
     }
@@ -3743,8 +3779,12 @@ fun com.google.protobuf_test_messages.proto3.TestAllTypesProto3Internal.MapSint3
             }
 
             else -> { 
+                if (tag.wireType == kotlinx.rpc.protobuf.internal.WireType.END_GROUP) { 
+                    throw kotlinx.rpc.protobuf.internal.ProtobufDecodingException("Unexpected END_GROUP tag.")
+                }
+
                 // we are currently just skipping unknown fields (KRPC-191)
-                decoder.skipValue(tag.wireType)
+                decoder.skipValue(tag)
             }
         }
     }
@@ -3798,8 +3838,12 @@ fun com.google.protobuf_test_messages.proto3.TestAllTypesProto3Internal.MapSint6
             }
 
             else -> { 
+                if (tag.wireType == kotlinx.rpc.protobuf.internal.WireType.END_GROUP) { 
+                    throw kotlinx.rpc.protobuf.internal.ProtobufDecodingException("Unexpected END_GROUP tag.")
+                }
+
                 // we are currently just skipping unknown fields (KRPC-191)
-                decoder.skipValue(tag.wireType)
+                decoder.skipValue(tag)
             }
         }
     }
@@ -3853,8 +3897,12 @@ fun com.google.protobuf_test_messages.proto3.TestAllTypesProto3Internal.MapFixed
             }
 
             else -> { 
+                if (tag.wireType == kotlinx.rpc.protobuf.internal.WireType.END_GROUP) { 
+                    throw kotlinx.rpc.protobuf.internal.ProtobufDecodingException("Unexpected END_GROUP tag.")
+                }
+
                 // we are currently just skipping unknown fields (KRPC-191)
-                decoder.skipValue(tag.wireType)
+                decoder.skipValue(tag)
             }
         }
     }
@@ -3908,8 +3956,12 @@ fun com.google.protobuf_test_messages.proto3.TestAllTypesProto3Internal.MapFixed
             }
 
             else -> { 
+                if (tag.wireType == kotlinx.rpc.protobuf.internal.WireType.END_GROUP) { 
+                    throw kotlinx.rpc.protobuf.internal.ProtobufDecodingException("Unexpected END_GROUP tag.")
+                }
+
                 // we are currently just skipping unknown fields (KRPC-191)
-                decoder.skipValue(tag.wireType)
+                decoder.skipValue(tag)
             }
         }
     }
@@ -3963,8 +4015,12 @@ fun com.google.protobuf_test_messages.proto3.TestAllTypesProto3Internal.MapSfixe
             }
 
             else -> { 
+                if (tag.wireType == kotlinx.rpc.protobuf.internal.WireType.END_GROUP) { 
+                    throw kotlinx.rpc.protobuf.internal.ProtobufDecodingException("Unexpected END_GROUP tag.")
+                }
+
                 // we are currently just skipping unknown fields (KRPC-191)
-                decoder.skipValue(tag.wireType)
+                decoder.skipValue(tag)
             }
         }
     }
@@ -4018,8 +4074,12 @@ fun com.google.protobuf_test_messages.proto3.TestAllTypesProto3Internal.MapSfixe
             }
 
             else -> { 
+                if (tag.wireType == kotlinx.rpc.protobuf.internal.WireType.END_GROUP) { 
+                    throw kotlinx.rpc.protobuf.internal.ProtobufDecodingException("Unexpected END_GROUP tag.")
+                }
+
                 // we are currently just skipping unknown fields (KRPC-191)
-                decoder.skipValue(tag.wireType)
+                decoder.skipValue(tag)
             }
         }
     }
@@ -4073,8 +4133,12 @@ fun com.google.protobuf_test_messages.proto3.TestAllTypesProto3Internal.MapInt32
             }
 
             else -> { 
+                if (tag.wireType == kotlinx.rpc.protobuf.internal.WireType.END_GROUP) { 
+                    throw kotlinx.rpc.protobuf.internal.ProtobufDecodingException("Unexpected END_GROUP tag.")
+                }
+
                 // we are currently just skipping unknown fields (KRPC-191)
-                decoder.skipValue(tag.wireType)
+                decoder.skipValue(tag)
             }
         }
     }
@@ -4128,8 +4192,12 @@ fun com.google.protobuf_test_messages.proto3.TestAllTypesProto3Internal.MapInt32
             }
 
             else -> { 
+                if (tag.wireType == kotlinx.rpc.protobuf.internal.WireType.END_GROUP) { 
+                    throw kotlinx.rpc.protobuf.internal.ProtobufDecodingException("Unexpected END_GROUP tag.")
+                }
+
                 // we are currently just skipping unknown fields (KRPC-191)
-                decoder.skipValue(tag.wireType)
+                decoder.skipValue(tag)
             }
         }
     }
@@ -4183,8 +4251,12 @@ fun com.google.protobuf_test_messages.proto3.TestAllTypesProto3Internal.MapBoolB
             }
 
             else -> { 
+                if (tag.wireType == kotlinx.rpc.protobuf.internal.WireType.END_GROUP) { 
+                    throw kotlinx.rpc.protobuf.internal.ProtobufDecodingException("Unexpected END_GROUP tag.")
+                }
+
                 // we are currently just skipping unknown fields (KRPC-191)
-                decoder.skipValue(tag.wireType)
+                decoder.skipValue(tag)
             }
         }
     }
@@ -4238,8 +4310,12 @@ fun com.google.protobuf_test_messages.proto3.TestAllTypesProto3Internal.MapStrin
             }
 
             else -> { 
+                if (tag.wireType == kotlinx.rpc.protobuf.internal.WireType.END_GROUP) { 
+                    throw kotlinx.rpc.protobuf.internal.ProtobufDecodingException("Unexpected END_GROUP tag.")
+                }
+
                 // we are currently just skipping unknown fields (KRPC-191)
-                decoder.skipValue(tag.wireType)
+                decoder.skipValue(tag)
             }
         }
     }
@@ -4293,8 +4369,12 @@ fun com.google.protobuf_test_messages.proto3.TestAllTypesProto3Internal.MapStrin
             }
 
             else -> { 
+                if (tag.wireType == kotlinx.rpc.protobuf.internal.WireType.END_GROUP) { 
+                    throw kotlinx.rpc.protobuf.internal.ProtobufDecodingException("Unexpected END_GROUP tag.")
+                }
+
                 // we are currently just skipping unknown fields (KRPC-191)
-                decoder.skipValue(tag.wireType)
+                decoder.skipValue(tag)
             }
         }
     }
@@ -4355,8 +4435,12 @@ fun com.google.protobuf_test_messages.proto3.TestAllTypesProto3Internal.MapStrin
             }
 
             else -> { 
+                if (tag.wireType == kotlinx.rpc.protobuf.internal.WireType.END_GROUP) { 
+                    throw kotlinx.rpc.protobuf.internal.ProtobufDecodingException("Unexpected END_GROUP tag.")
+                }
+
                 // we are currently just skipping unknown fields (KRPC-191)
-                decoder.skipValue(tag.wireType)
+                decoder.skipValue(tag)
             }
         }
     }
@@ -4417,8 +4501,12 @@ fun com.google.protobuf_test_messages.proto3.TestAllTypesProto3Internal.MapStrin
             }
 
             else -> { 
+                if (tag.wireType == kotlinx.rpc.protobuf.internal.WireType.END_GROUP) { 
+                    throw kotlinx.rpc.protobuf.internal.ProtobufDecodingException("Unexpected END_GROUP tag.")
+                }
+
                 // we are currently just skipping unknown fields (KRPC-191)
-                decoder.skipValue(tag.wireType)
+                decoder.skipValue(tag)
             }
         }
     }
@@ -4472,8 +4560,12 @@ fun com.google.protobuf_test_messages.proto3.TestAllTypesProto3Internal.MapStrin
             }
 
             else -> { 
+                if (tag.wireType == kotlinx.rpc.protobuf.internal.WireType.END_GROUP) { 
+                    throw kotlinx.rpc.protobuf.internal.ProtobufDecodingException("Unexpected END_GROUP tag.")
+                }
+
                 // we are currently just skipping unknown fields (KRPC-191)
-                decoder.skipValue(tag.wireType)
+                decoder.skipValue(tag)
             }
         }
     }
@@ -4527,8 +4619,12 @@ fun com.google.protobuf_test_messages.proto3.TestAllTypesProto3Internal.MapStrin
             }
 
             else -> { 
+                if (tag.wireType == kotlinx.rpc.protobuf.internal.WireType.END_GROUP) { 
+                    throw kotlinx.rpc.protobuf.internal.ProtobufDecodingException("Unexpected END_GROUP tag.")
+                }
+
                 // we are currently just skipping unknown fields (KRPC-191)
-                decoder.skipValue(tag.wireType)
+                decoder.skipValue(tag)
             }
         }
     }
diff --git a/tests/protobuf-conformance/src/test/kotlin/kotlinx/rpc/protoc/gen/test/ConformanceTest.kt b/tests/protobuf-conformance/src/test/kotlin/kotlinx/rpc/protoc/gen/test/ConformanceTest.kt
index e2e21c640..14dce3c77 100644
--- a/tests/protobuf-conformance/src/test/kotlin/kotlinx/rpc/protoc/gen/test/ConformanceTest.kt
+++ b/tests/protobuf-conformance/src/test/kotlin/kotlinx/rpc/protoc/gen/test/ConformanceTest.kt
@@ -84,11 +84,11 @@ class ConformanceTest {
 
         return (fails.entries.map { (test, message) ->
             DynamicTest.dynamicTest(test.testDisplayName()) {
-                fail(message)
+                fail("FAILED: '${test}' with: $message")
             }
         } + passed.map { test ->
             DynamicTest.dynamicTest(test.testDisplayName()) {
-                println("PASSED")
+                println("PASSED: '${test}'")
             }
         }).stream()
     }