diff --git a/firebase-vertexai/src/test/java/com/google/firebase/vertexai/common/UnarySnapshotTests.kt b/firebase-vertexai/src/test/java/com/google/firebase/vertexai/common/UnarySnapshotTests.kt
index 6749a31e952..66e6a3f53a5 100644
--- a/firebase-vertexai/src/test/java/com/google/firebase/vertexai/common/UnarySnapshotTests.kt
+++ b/firebase-vertexai/src/test/java/com/google/firebase/vertexai/common/UnarySnapshotTests.kt
@@ -35,6 +35,7 @@ import io.kotest.matchers.types.shouldBeInstanceOf
 import io.ktor.http.HttpStatusCode
 import kotlin.time.Duration.Companion.seconds
 import kotlinx.coroutines.withTimeout
+import kotlinx.serialization.ExperimentalSerializationApi
 import kotlinx.serialization.Serializable
 import kotlinx.serialization.json.JsonPrimitive
 import org.junit.Test
@@ -44,6 +45,7 @@ import org.junit.Test
 internal class UnarySnapshotTests {
   private val testTimeout = 5.seconds
 
+  @OptIn(ExperimentalSerializationApi::class)
   @Test
   fun `short reply`() =
     goldenUnaryFile("success-basic-reply-short.json") {
@@ -57,6 +59,7 @@ internal class UnarySnapshotTests {
       }
     }
 
+  @OptIn(ExperimentalSerializationApi::class)
   @Test
   fun `long reply`() =
     goldenUnaryFile("success-basic-reply-long.json") {
@@ -219,6 +222,7 @@ internal class UnarySnapshotTests {
       }
     }
 
+  @OptIn(ExperimentalSerializationApi::class)
   @Test
   fun `properly translates json text`() =
     goldenUnaryFile("success-constraint-decoding-json.json") {
@@ -305,6 +309,7 @@ internal class UnarySnapshotTests {
       }
     }
 
+  @OptIn(ExperimentalSerializationApi::class)
   @Test
   fun `function call contains null param`() =
     goldenUnaryFile("success-function-call-null.json") {
@@ -317,6 +322,7 @@ internal class UnarySnapshotTests {
       }
     }
 
+  @OptIn(ExperimentalSerializationApi::class)
   @Test
   fun `function call contains json literal`() =
     goldenUnaryFile("success-function-call-json-literal.json") {
@@ -335,6 +341,7 @@ internal class UnarySnapshotTests {
       }
     }
 
+  @OptIn(ExperimentalSerializationApi::class)
   @Test
   fun `function call has no arguments field`() =
     goldenUnaryFile("success-function-call-empty-arguments.json") {
diff --git a/firebase-vertexai/src/test/java/com/google/firebase/vertexai/common/util/tests.kt b/firebase-vertexai/src/test/java/com/google/firebase/vertexai/common/util/tests.kt
index db42d791c30..8d1e3bf9f00 100644
--- a/firebase-vertexai/src/test/java/com/google/firebase/vertexai/common/util/tests.kt
+++ b/firebase-vertexai/src/test/java/com/google/firebase/vertexai/common/util/tests.kt
@@ -38,6 +38,7 @@ import io.ktor.utils.io.close
 import io.ktor.utils.io.writeFully
 import java.io.File
 import kotlinx.coroutines.launch
+import kotlinx.serialization.ExperimentalSerializationApi
 import kotlinx.serialization.encodeToString
 
 private val TEST_CLIENT_ID = "genai-android/test"
@@ -48,6 +49,7 @@ internal fun prepareStreamingResponse(response: List<GenerateContentResponse>):
 internal fun prepareResponse(response: GenerateContentResponse) =
   JSON.encodeToString(response).toByteArray()
 
+@OptIn(ExperimentalSerializationApi::class)
 internal fun createRequest(vararg text: String): GenerateContentRequest {
   val contents = text.map { Content(parts = listOf(TextPart(it))) }
 
@@ -56,6 +58,7 @@ internal fun createRequest(vararg text: String): GenerateContentRequest {
 
 internal fun createResponse(text: String) = createResponses(text).single()
 
+@OptIn(ExperimentalSerializationApi::class)
 internal fun createResponses(vararg text: String): List<GenerateContentResponse> {
   val candidates = text.map { Candidate(Content(parts = listOf(TextPart(it)))) }