diff --git a/app/assets/javascripts/zen_mode.js.coffee b/app/assets/javascripts/zen_mode.js.coffee
index 6c220650998260974f5fa17e1e84265910e21f59..d28b635355eff4f05b81400b165c4b01ddaa6d95 100644
--- a/app/assets/javascripts/zen_mode.js.coffee
+++ b/app/assets/javascripts/zen_mode.js.coffee
@@ -16,6 +16,7 @@ class @ZenMode
     $(document).on 'keydown', (e) =>
       if e.keyCode is $.ui.keyCode.ESCAPE
         @exitZenMode()
+        e.preventDefault()
 
     $(window).on 'hashchange', @updateZenModeFromLocationHash