diff --git a/IPython/frontend/html/notebook/static/js/examples/celltoolbar.example.js b/IPython/frontend/html/notebook/static/js/examples/celltoolbar.example.js
index b5aa77a..d39cc18 100644
--- a/IPython/frontend/html/notebook/static/js/examples/celltoolbar.example.js
+++ b/IPython/frontend/html/notebook/static/js/examples/celltoolbar.example.js
@@ -105,7 +105,7 @@
                         cell.code_mirror.setOption('readOnly','nocursor')
                         button.button('option','icons',{primary:'ui-icon-locked'})
                     } else {
-                        cell.code_mirror.setOption('readOnly','false')
+                        cell.code_mirror.setOption('readOnly',false)
                         button.button('option','icons',{primary:'ui-icon-unlocked'})
                     }
                 } catch(e){}