diff --git a/lib/server.js b/lib/server.js
index e3f6f9416..c623b1e9c 100644
--- a/lib/server.js
+++ b/lib/server.js
@@ -197,7 +197,11 @@ var start = function(injector, config, launcher, globalEmitter, preprocess, file
     // TODO(vojta): change the client to not send the event (if disconnected by purpose)
     var sockets = socketServer.sockets.sockets;
     Object.getOwnPropertyNames(sockets).forEach(function(key) {
-      sockets[key].removeAllListeners('disconnect');
+      var socket = sockets[key];
+      socket.removeAllListeners('disconnect');
+      if (!socket.disconnected) {
+        socket.disconnect();
+      }
     });
 
     var removeAllListenersDone = false;