diff --git a/script.js b/script.js
index 8480130..d3425c9 100644
--- a/script.js
+++ b/script.js
@@ -56,6 +56,8 @@ function sketchHandler(){
     addColorToCell(e.target, inkMode)
 
     sketchBoard.addEventListener('mouseover', highlightCallback)
+    window.addEventListener('mouseup', clearHighlightCallback);
+
   })
     
   // detaching the mouseover events to prevent unnecessary sketch-cell coloring