Fix test
diff --git a/lib/test_reflective_loader.dart b/lib/test_reflective_loader.dart
index cfd738d..3528a43 100644
--- a/lib/test_reflective_loader.dart
+++ b/lib/test_reflective_loader.dart
@@ -252,7 +252,7 @@
 Future<Object?>? _runFailingTest(ClassMirror classMirror, Symbol symbol) {
   bool passed = false;
   return runZonedGuarded(() {
-    return new Future.sync(() => _runTest(classMirror, symbol)).then((_) {
+    return new Future.sync(() => _runTest(classMirror, symbol)).then<void>((_) {
       passed = true;
       test_package.fail('Test passed - expected to fail.');
     }).catchError((e) {