diff --git a/codegen-server/src/main/kotlin/software/amazon/smithy/rust/codegen/server/smithy/generators/protocol/ServerProtocolTestGenerator.kt b/codegen-server/src/main/kotlin/software/amazon/smithy/rust/codegen/server/smithy/generators/protocol/ServerProtocolTestGenerator.kt
index 4f4df441dfccff7cbaed345d8cca88158fd16736..6f90dfcb15097255f3234a98d3372b1db39e34af 100644
--- a/codegen-server/src/main/kotlin/software/amazon/smithy/rust/codegen/server/smithy/generators/protocol/ServerProtocolTestGenerator.kt
+++ b/codegen-server/src/main/kotlin/software/amazon/smithy/rust/codegen/server/smithy/generators/protocol/ServerProtocolTestGenerator.kt
@@ -92,9 +92,9 @@ class ServerProtocolTestGenerator(
             ?.getTestCasesFor(AppliesTo.SERVER).orEmpty().map { TestCase.RequestTest(it, inputShape) }
         val responseTests = operationShape.getTrait<HttpResponseTestsTrait>()
             ?.getTestCasesFor(AppliesTo.SERVER).orEmpty().map { TestCase.ResponseTest(it, outputShape) }
-
         val errorTests = operationIndex.getErrors(operationShape).flatMap { error ->
-            val testCases = error.getTrait<HttpResponseTestsTrait>()?.testCases.orEmpty()
+            val testCases = error.getTrait<HttpResponseTestsTrait>()
+                ?.getTestCasesFor(AppliesTo.SERVER).orEmpty()
             testCases.map { TestCase.ResponseTest(it, error) }
         }
         val allTests: List<TestCase> = (requestTests + responseTests + errorTests).filterMatching().fixBroken()
diff --git a/codegen/src/main/kotlin/software/amazon/smithy/rust/codegen/smithy/generators/protocol/ProtocolTestGenerator.kt b/codegen/src/main/kotlin/software/amazon/smithy/rust/codegen/smithy/generators/protocol/ProtocolTestGenerator.kt
index a54da64a78d03500f857caf012351f42af369f6c..22266bcc8a86df307fd80ddf621d23ce35a0ac06 100644
--- a/codegen/src/main/kotlin/software/amazon/smithy/rust/codegen/smithy/generators/protocol/ProtocolTestGenerator.kt
+++ b/codegen/src/main/kotlin/software/amazon/smithy/rust/codegen/smithy/generators/protocol/ProtocolTestGenerator.kt
@@ -97,9 +97,9 @@ class ProtocolTestGenerator(
             ?.getTestCasesFor(AppliesTo.CLIENT).orEmpty().map { TestCase.RequestTest(it) }
         val responseTests = operationShape.getTrait<HttpResponseTestsTrait>()
             ?.getTestCasesFor(AppliesTo.CLIENT).orEmpty().map { TestCase.ResponseTest(it, outputShape) }
-
         val errorTests = operationIndex.getErrors(operationShape).flatMap { error ->
-            val testCases = error.getTrait<HttpResponseTestsTrait>()?.testCases.orEmpty()
+            val testCases = error.getTrait<HttpResponseTestsTrait>()
+                ?.getTestCasesFor(AppliesTo.CLIENT).orEmpty()
             testCases.map { TestCase.ResponseTest(it, error) }
         }
         val allTests: List<TestCase> = (requestTests + responseTests + errorTests).filterMatching()