diff --git a/lib/dns.js b/lib/dns.js
index 55351bb77480c7..9a81dfffd6d803 100644
--- a/lib/dns.js
+++ b/lib/dns.js
@@ -293,7 +293,7 @@ exports.setServers = function(servers) {
     if (ipVersion !== 0)
       return newSet.push([ipVersion, serv]);
 
-    const match = serv.match(/\[(.*)\](:\d+)?/);
+    const match = serv.match(/\[(.*)\](?::\d+)?/);
     // we have an IPv6 in brackets
     if (match) {
       ipVersion = isIP(match[1]);