diff --git a/pkg/ruler/rule_concurrency_test.go b/pkg/ruler/rule_concurrency_test.go
index 9d18982ef4..e7c485db30 100644
--- a/pkg/ruler/rule_concurrency_test.go
+++ b/pkg/ruler/rule_concurrency_test.go
@@ -244,6 +244,10 @@ func TestSplitGroupIntoBatches(t *testing.T) {
 
 			batches := controller.SplitGroupIntoBatches(context.Background(), group)
 			requireConcurrentRulesEqual(t, tc.expectedGroups, batches)
+
+			// Make sure the group is not mutated and will still return the same batches when called again.
+			batches = controller.SplitGroupIntoBatches(context.Background(), group)
+			requireConcurrentRulesEqual(t, tc.expectedGroups, batches)
 		})
 	}
 }