diff --git a/app/lib/rocketchat.js b/app/lib/rocketchat.js
index 1cb08a98a..97faaac0b 100644
--- a/app/lib/rocketchat.js
+++ b/app/lib/rocketchat.js
@@ -42,7 +42,7 @@ const RocketChat = {
 		}
 	},
 	async testServer(url) {
-		if (/^(https?:\/\/)?(((\w|[0-9])+(\.(\w|[0-9-_])+)+)|localhost)(:\d+)?$/.test(url)) {
+		if (/^(https?:\/\/)?(((\w|[0-9-_])+(\.(\w|[0-9-_])+)+)|localhost)(:\d+)?$/.test(url)) {
 			const response = await fetch(url, { method: 'HEAD' });
 			if (response.status === 200 && response.headers.get('x-instance-id') != null && response.headers.get('x-instance-id').length) {
 				return url;