diff --git a/pkg/url/validator.go b/pkg/url/validator.go
index 81e81d7..c14b3d6 100644
--- a/pkg/url/validator.go
+++ b/pkg/url/validator.go
@@ -129,6 +129,10 @@ func isValidAbsolutePath(redirect string) bool {
 }
 
 func isAllowedDomain(u *url.URL, allowed string) bool {
+	if len(allowed) == 0 {
+		return false
+	}
+
 	host := u.Host
 	hostname := u.Hostname()