diff --git a/src/xterm.js b/src/xterm.js
index 515e976d..94257e24 100644
--- a/src/xterm.js
+++ b/src/xterm.js
@@ -2346,7 +2346,7 @@
           break;
         default:
           // a-z and space
-          if (ev.ctrlKey) {
+          if (ev.ctrlKey && !ev.shiftKey && !ev.altKey && !ev.metaKey) {
             if (ev.keyCode >= 65 && ev.keyCode <= 90) {
               key = String.fromCharCode(ev.keyCode - 64);
             } else if (ev.keyCode === 32) {