diff --git a/test/comparators_test.dart b/test/comparators_test.dart
index 4762d17..3df0812 100644
--- a/test/comparators_test.dart
+++ b/test/comparators_test.dart
@@ -57,7 +57,7 @@
     "~"
   ];
 
-  void sortedBy(int compare(String a, String b)) => strings.toList()
+  List<String> sortedBy(int compare(String a, String b)) => strings.toList()
     ..shuffle()
     ..sort(compare);