diff --git a/lib/http-proxy/common.js b/lib/http-proxy/common.js
index 7c374b0c8..693198af3 100644
--- a/lib/http-proxy/common.js
+++ b/lib/http-proxy/common.js
@@ -54,7 +54,7 @@ common.setupOutgoing = function(outgoing, options, req, forward) {
   if (!outgoing.agent) {
     outgoing.headers = outgoing.headers || {};
     if (typeof outgoing.headers.connection !== 'string'
-        || ! upgradeHeader.test(outgoing.headers.connection)
+        || !upgradeHeader.test(outgoing.headers.connection)
        ) { outgoing.headers.connection = 'close'; }
   }