diff --git a/src/addons/attach/attach.js b/src/addons/attach/attach.js
index c2a7989..2e11062 100644
--- a/src/addons/attach/attach.js
+++ b/src/addons/attach/attach.js
@@ -66,6 +66,10 @@
     };
 
     term._sendData = function (data) {
+      if (socket.readyState !== 1) {
+        return;
+      }
+
       socket.send(data);
     };