diff --git a/interop/bin/server.dart b/interop/bin/server.dart
index 29a1f6b..812210e 100644
--- a/interop/bin/server.dart
+++ b/interop/bin/server.dart
@@ -114,8 +114,9 @@ class TestService extends TestServiceBase {
   }
 
   @override
-  Future<Empty> unimplementedCall(ServiceCall call, Empty request) async {
-    return Empty();
+  Future<Empty> unimplementedCall(ServiceCall call, Empty request) {
+    call.sendTrailers(status: StatusCode.unimplemented);
+    return null;
   }
 }
 
diff --git a/interop/lib/src/client.dart b/interop/lib/src/client.dart
index 2c3e4cc..2cb93c8 100644
--- a/interop/lib/src/client.dart
+++ b/interop/lib/src/client.dart
@@ -19,9 +19,9 @@ import 'dart:typed_data';
 
 import 'package:collection/collection.dart';
 import 'package:grpc/grpc.dart';
-import 'package:interop/src/generated/empty.pb.dart';
-import 'package:interop/src/generated/messages.pb.dart';
-import 'package:interop/src/generated/test.pbgrpc.dart';
+import 'generated/empty.pb.dart';
+import 'generated/messages.pb.dart';
+import 'generated/test.pbgrpc.dart';
 
 const _headerEchoKey = 'x-grpc-test-echo-initial';
 const _headerEchoData = 'test_initial_metadata_value';