Fix writer test on mac
diff --git a/test/writer_test.dart b/test/writer_test.dart
index 12aece0..45469e4 100644
--- a/test/writer_test.dart
+++ b/test/writer_test.dart
@@ -50,7 +50,8 @@
           contains('-rwxr--r--'),
           contains('my_user'),
           contains('long group that exceeds 32 characters'),
-          contains('12:34'),
+          // The date format is different across GNU and BSD tar
+          anyOf(contains('12:34'), contains('Dec 30')),
         ),
       ),
     );