diff --git a/src/js/login.js b/src/js/login.js
index df8cf35..f16b4fa 100644
--- a/src/js/login.js
+++ b/src/js/login.js
@@ -16,7 +16,7 @@ const password = q("#password")
 //			6: IPv6 address
 //		MAYBE WITH
 //		7: port number
-const RE_LOSSY_MXID = new RegExp(`^@?([a-z0-9._=-]+?)(?::((?:(${S_RE_DOMAIN})|((${S_RE_IPV4})|(${S_RE_IPV6})))(?::(\\d+))?))?$`)
+const RE_LOSSY_MXID = new RegExp(`^@?([a-z0-9._=-]+?)(?::((?:(${S_RE_DOMAIN})|((${S_RE_IPV4})|(\\[${S_RE_IPV6}])))(?::(\\d+))?))?$`)
 
 window.RE_LOSSY_MXID = RE_LOSSY_MXID