diff --git a/test/find_default_locale_browser_test.dart b/test/find_default_locale_browser_test.dart
index fbbdcd1..818194e 100644
--- a/test/find_default_locale_browser_test.dart
+++ b/test/find_default_locale_browser_test.dart
@@ -15,7 +15,7 @@
     // should find a way to force the system locale before the test is run
     // and then verify that it's actually the correct value.
     Intl.systemLocale = 'xx_YY';
-    ThenArgument callback = expectAsync1(verifyLocale) as ThenArgument;
+    ThenArgument callback = expectAsync1(verifyLocale);
     findSystemLocale().then(callback);
   });
 }
diff --git a/test/find_default_locale_standalone_test.dart b/test/find_default_locale_standalone_test.dart
index 033ad46..21bf17b 100644
--- a/test/find_default_locale_standalone_test.dart
+++ b/test/find_default_locale_standalone_test.dart
@@ -14,7 +14,7 @@
     // and then verify that it's actually the correct value.
     // We have no way of getting this reliably for Windows, so it will fail.
     Intl.systemLocale = "xx_YY";
-    var callback = expectAsync1(verifyLocale) as ThenArgument;
+    var callback = expectAsync1(verifyLocale);
     findSystemLocale().then(callback);
   });
 }