diff --git a/lib/x11/xcore.js b/lib/x11/xcore.js
index 2206acb..bb96846 100644
--- a/lib/x11/xcore.js
+++ b/lib/x11/xcore.js
@@ -353,6 +353,9 @@ module.exports.createClient = function(initCb, display, options)
         display = ':0';
 
     var displayMatch = display.match(/^(?:[^:]*?\/)?(.*):(\d+)(?:.(\d+))?$/);
+    if (!displayMatch)
+       throw new Error("Cannot parse display");
+
     var host = displayMatch[1];
     if (!host)
         host = '127.0.0.1';