diff --git a/utils.ts b/utils.ts
index 7f30dfa..2e40643 100644
--- a/utils.ts
+++ b/utils.ts
@@ -4,6 +4,7 @@ export const utf8Decoder = new TextDecoder('utf-8')
 export const utf8Encoder = new TextEncoder()
 
 export function normalizeURL(url: string): string {
+  if (url.indexOf('://') === -1) url = 'wss://' + url
   let p = new URL(url)
   p.pathname = p.pathname.replace(/\/+/g, '/')
   if (p.pathname.endsWith('/')) p.pathname = p.pathname.slice(0, -1)