diff --git a/test/pending_driver_test.dart b/test/pending_driver_test.dart
index fe3818e..83d5899 100644
--- a/test/pending_driver_test.dart
+++ b/test/pending_driver_test.dart
@@ -140,7 +140,7 @@ void main() {
   group('end of test empty check', () {
     test('not empty at end of test fails', () async {
       // end the test prematurely
-      Simulator.registerAction(200, Simulator.endSimulation);
+      Simulator.registerAction(200, () => unawaited(Simulator.endSimulation()));
 
       final myTest = MyTest(clk: clk!)..printLevel = Level.OFF;
       try {
@@ -152,7 +152,7 @@ void main() {
 
     test('disable end of test empty check', () async {
       // end the test prematurely
-      Simulator.registerAction(200, Simulator.endSimulation);
+      Simulator.registerAction(200, () => unawaited(Simulator.endSimulation()));
 
       final myTest = MyTest(
         clk: clk!,
diff --git a/test/test_test.dart b/test/test_test.dart
index 63ea30e..9bf1ede 100644
--- a/test/test_test.dart
+++ b/test/test_test.dart
@@ -21,7 +21,7 @@ class ForeverObjectionTest extends Test {
     unawaited(super.run(phase));
     phase.raiseObjection('objectionNeverCloses');
     SimpleClockGenerator(10);
-    Simulator.registerAction(100, Simulator.endSimulation);
+    Simulator.registerAction(100, () => unawaited(Simulator.endSimulation()));
   }
 }