diff --git a/apps/backlite/boot.js b/apps/backlite/boot.js
index f3a4de589..9f01b4676 100644
--- a/apps/backlite/boot.js
+++ b/apps/backlite/boot.js
@@ -13,7 +13,7 @@
   s.brightness = 0;
   require("Storage").writeJSON("setting.json", s);
   //remove large settings object from memory
-  s=null;
+  delete s;
   const longPressTime=400; //(ms)
 
   Bangle.on('lock', function(isLocked) {