diff --git a/lib/poplib.js b/lib/poplib.js
index 17a83ad..62464ee 100644
--- a/lib/poplib.js
+++ b/lib/poplib.js
@@ -100,9 +100,11 @@ function POP3Client(port, host, options) {
     var checkResp = true;
     var err = null;
     var detach = function() {
+     if (socket !== null) {
       socket.removeAllListeners("data");
       socket.removeAllListeners("error");
       socket.removeAllListeners("close");
+     }
     };
 
     socket.on("data", function(data) {
@@ -640,4 +642,4 @@ POP3Client.prototype.quit = function(cb) {
   });
 };
 
-module.exports = POP3Client;
\ No newline at end of file
+module.exports = POP3Client;