diff --git a/src/iceberg/json_internal.cc b/src/iceberg/json_internal.cc
index 3614ed230..e3e66116e 100644
--- a/src/iceberg/json_internal.cc
+++ b/src/iceberg/json_internal.cc
@@ -43,6 +43,7 @@
 #include "iceberg/util/formatter.h"  // IWYU pragma: keep
 #include "iceberg/util/macros.h"
 #include "iceberg/util/timepoint.h"
+#include "iceberg/util/unreachable.h"
 
 namespace iceberg {
 
@@ -477,6 +478,8 @@ nlohmann::json ToJson(const Type& type) {
     case TypeId::kUuid:
       return "uuid";
   }
+  internal::Unreachable(
+      std::format("Unknown type id: {}", static_cast<int>(type.type_id())));
 }
 
 nlohmann::json ToJson(const Schema& schema) {
diff --git a/src/iceberg/schema_util.cc b/src/iceberg/schema_util.cc
index 3e409efd7..4139a2b38 100644
--- a/src/iceberg/schema_util.cc
+++ b/src/iceberg/schema_util.cc
@@ -29,6 +29,7 @@
 #include "iceberg/util/checked_cast.h"
 #include "iceberg/util/formatter_internal.h"
 #include "iceberg/util/macros.h"
+#include "iceberg/util/unreachable.h"
 
 namespace iceberg {
 
@@ -172,6 +173,8 @@ std::string_view ToString(FieldProjection::Kind kind) {
     case FieldProjection::Kind::kNull:
       return "null";
   }
+  internal::Unreachable(
+      std::format("Unknown field projection kind: {}", static_cast<int>(kind)));
 }
 
 std::string ToString(const FieldProjection& projection) {
diff --git a/src/iceberg/transform.cc b/src/iceberg/transform.cc
index dc0529766..95f6fe717 100644
--- a/src/iceberg/transform.cc
+++ b/src/iceberg/transform.cc
@@ -24,6 +24,7 @@
 
 #include "iceberg/transform_function.h"
 #include "iceberg/type.h"
+#include "iceberg/util/unreachable.h"
 
 namespace iceberg {
 namespace {
@@ -59,6 +60,8 @@ constexpr std::string_view TransformTypeToString(TransformType type) {
     case TransformType::kVoid:
       return kVoidName;
   }
+  internal::Unreachable(
+      std::format("Unknown transform type: {}", static_cast<int>(type)));
 }
 
 std::shared_ptr<Transform> Transform::Identity() {
@@ -166,6 +169,8 @@ std::string Transform::ToString() const {
       return std::format("{}[{}]", TransformTypeToString(transform_type_),
                          std::get<int32_t>(param_));
   }
+  internal::Unreachable(
+      std::format("Unknown transform type: {}", static_cast<int>(transform_type_)));
 }
 
 TransformFunction::TransformFunction(TransformType transform_type,