diff --git a/js/src/console.js b/js/src/console.js
index 2fc0a17fdd..8049d3d546 100644
--- a/js/src/console.js
+++ b/js/src/console.js
@@ -538,7 +538,7 @@ var ConsoleInput = {
         if (ConsoleInput.inputs !== null) {
             return;
         }
-        if (typeof CodeMirror !== 'undefined') {
+        if (typeof CodeMirror !== 'undefined' && typeof CodeMirror.runMode === 'function') {
             ConsoleInput.codeMirror = true;
         }
         ConsoleInput.inputs = [];