diff --git a/guacamole-common-js/src/main/webapp/modules/Tunnel.js b/guacamole-common-js/src/main/webapp/modules/Tunnel.js
index 8954c5245..b990ed121 100644
--- a/guacamole-common-js/src/main/webapp/modules/Tunnel.js
+++ b/guacamole-common-js/src/main/webapp/modules/Tunnel.js
@@ -214,6 +214,10 @@ Guacamole.HTTPTunnel = function(tunnelURL) {
 
         // Mark as closed
         tunnel.state = Guacamole.Tunnel.State.CLOSED;
+
+        // Reset output message buffer
+        sendingMessages = false;
+
         if (tunnel.onstatechange)
             tunnel.onstatechange(tunnel.state);