diff --git a/lib/dns.js b/lib/dns.js
index d577023b50c440..0aeffca03b93a2 100644
--- a/lib/dns.js
+++ b/lib/dns.js
@@ -292,7 +292,7 @@ exports.setServers = function(servers) {
     if (ver)
       return newSet.push([ver, serv]);
 
-    var match = serv.match(/\[(.*)\](:\d+)?/);
+    var match = serv.match(/\[(.*)\](?::\d+)?/);
 
     // we have an IPv6 in brackets
     if (match) {