diff --git a/pkgs/corpus/test/pub_test.dart b/pkgs/corpus/test/pub_test.dart
index 9afcd793..d1a82150 100644
--- a/pkgs/corpus/test/pub_test.dart
+++ b/pkgs/corpus/test/pub_test.dart
@@ -31,7 +31,7 @@ extension VersionConstraintChecks on Check<VersionConstraint> {
   void allows(String version) {
     context.expect(() => const ['allows'], (VersionConstraint actual) {
       final ver = Version.parse(version);
-      if (!actual.allows(ver)) return Rejection(actual: '$actual');
+      if (!actual.allows(ver)) return Rejection(actual: ['$actual']);
       return null;
     });
   }