diff --git a/dart/crosstest/go_dart_client.dart b/dart/crosstest/go_dart_client.dart
index b3b7cf4..a79a26c 100644
--- a/dart/crosstest/go_dart_client.dart
+++ b/dart/crosstest/go_dart_client.dart
@@ -73,6 +73,7 @@ Future<void> main(List<String> args) async {
   if (!ok) {
     exitCode = 1;
   }
+  exit(exitCode);
 }
 
 Future<_ClientHandle> _connectWithRetry(String mode, int port) async {
diff --git a/dart/crosstest/kotlin_dart_client.dart b/dart/crosstest/kotlin_dart_client.dart
index cac150d..74ea9c1 100644
--- a/dart/crosstest/kotlin_dart_client.dart
+++ b/dart/crosstest/kotlin_dart_client.dart
@@ -73,6 +73,7 @@ Future<void> main(List<String> args) async {
   if (!ok) {
     exitCode = 1;
   }
+  exit(exitCode);
 }
 
 Future<_ClientHandle> _connectWithRetry(String mode, int port) async {