diff --git a/example/server/storage/storage.go b/example/server/storage/storage.go
index 3112e81..7c1728b 100644
--- a/example/server/storage/storage.go
+++ b/example/server/storage/storage.go
@@ -615,6 +615,9 @@ func (s *Storage) renewRefreshToken(currentRefreshToken string) (string, string,
 			break
 		}
 	}
+	if refreshToken.Expiration.After(time.Now()) {
+		return "", "", fmt.Errorf("expired refresh token")
+	}
 	// creates a new refresh token based on the current one
 	token := uuid.NewString()
 	refreshToken.Token = token