diff --git a/pkg/ruler/rulestore/objectclient/rule_store.go b/pkg/ruler/rulestore/objectclient/rule_store.go
index 747cf728f6cc6..b945c298af0b9 100644
--- a/pkg/ruler/rulestore/objectclient/rule_store.go
+++ b/pkg/ruler/rulestore/objectclient/rule_store.go
@@ -54,7 +54,7 @@ func NewRuleStore(client chunk.ObjectClient, loadConcurrency int, logger log.Log
 func (o *RuleStore) getRuleGroup(ctx context.Context, objectKey string, rg *rulespb.RuleGroupDesc) (*rulespb.RuleGroupDesc, error) {
 	reader, _, err := o.client.GetObject(ctx, objectKey)
 	if err != nil {
-		if err.Error() == chunk.ErrStorageObjectNotFound.Error() {
+		if o.client.IsObjectNotFoundErr(err) {
 			level.Debug(o.logger).Log("msg", "rule group does not exist", "name", objectKey)
 			return nil, errors.Wrapf(rulestore.ErrGroupNotFound, "get rule group user=%q, namespace=%q, name=%q", rg.GetUser(), rg.GetNamespace(), rg.GetName())
 		}
@@ -214,7 +214,7 @@ func (o *RuleStore) SetRuleGroup(ctx context.Context, userID string, namespace s
 func (o *RuleStore) DeleteRuleGroup(ctx context.Context, userID string, namespace string, groupName string) error {
 	objectKey := generateRuleObjectKey(userID, namespace, groupName)
 	err := o.client.DeleteObject(ctx, objectKey)
-	if err == chunk.ErrStorageObjectNotFound {
+	if o.client.IsObjectNotFoundErr(err) {
 		return rulestore.ErrGroupNotFound
 	}
 	return err