diff --git a/helper/testing.go b/helper/testing.go
index 7f5fd1e..9142006 100644
--- a/helper/testing.go
+++ b/helper/testing.go
@@ -1,6 +1,7 @@
 package helper
 
 import (
+	"reflect"
 	"testing"
 
 	"github.com/google/go-cmp/cmp"
@@ -30,7 +31,7 @@ func AssertIssues(t *testing.T, expected Issues, actual Issues) {
 	opts := []cmp.Option{
 		// Byte field will be ignored because it's not important in tests such as positions
 		cmpopts.IgnoreFields(hcl.Pos{}, "Byte"),
-		cmpopts.IgnoreFields(Issue{}, "Rule"),
+		ruleComparer(),
 	}
 	if !cmp.Equal(expected, actual, opts...) {
 		t.Fatalf("Expected issues are not matched:\n %s\n", cmp.Diff(expected, actual, opts...))
@@ -41,9 +42,17 @@ func AssertIssues(t *testing.T, expected Issues, actual Issues) {
 func AssertIssuesWithoutRange(t *testing.T, expected Issues, actual Issues) {
 	opts := []cmp.Option{
 		cmpopts.IgnoreFields(Issue{}, "Range"),
-		cmpopts.IgnoreFields(Issue{}, "Rule"),
+		ruleComparer(),
 	}
 	if !cmp.Equal(expected, actual, opts...) {
 		t.Fatalf("Expected issues are not matched:\n %s\n", cmp.Diff(expected, actual, opts...))
 	}
 }
+
+// ruleComparer returns a Comparer func that checks that two rule interfaces
+// have the same underlying type. It does not compare struct fields.
+func ruleComparer() cmp.Option {
+	return cmp.Comparer(func(x, y Rule) bool {
+		return reflect.TypeOf(x) == reflect.TypeOf(y)
+	})
+}