diff --git a/option/rule_set.go b/option/rule_set.go
index 2775d743..fa839e35 100644
--- a/option/rule_set.go
+++ b/option/rule_set.go
@@ -258,7 +258,7 @@ func (r *PlainRuleSetCompat) UnmarshalJSON(bytes []byte) error {
 	}
 	var v any
 	switch r.Version {
-	case C.RuleSetVersion1, C.RuleSetVersion2, C.RuleSetVersion3:
+	case C.RuleSetVersion1, C.RuleSetVersion2, C.RuleSetVersion3, C.RuleSetVersion4:
 		v = &r.Options
 	case 0:
 		return E.New("missing rule-set version")
@@ -275,7 +275,7 @@ func (r *PlainRuleSetCompat) UnmarshalJSON(bytes []byte) error {
 
 func (r PlainRuleSetCompat) Upgrade() (PlainRuleSet, error) {
 	switch r.Version {
-	case C.RuleSetVersion1, C.RuleSetVersion2, C.RuleSetVersion3:
+	case C.RuleSetVersion1, C.RuleSetVersion2, C.RuleSetVersion3, C.RuleSetVersion4:
 	default:
 		return PlainRuleSet{}, E.New("unknown rule-set version: " + F.ToString(r.Version))
 	}