diff --git a/12/dragable.js b/12/dragable.js
index f2bc653..2345616 100644
--- a/12/dragable.js
+++ b/12/dragable.js
@@ -46,8 +46,8 @@
   dragObj.onmouseup = function(e) {
     if (dragObj) {
       dragObj = null;
-      dragObj.removeEventListener('mousemove', dragObject, true);
-      dragObj.removeEventListener('touchmove', dragObject, true);
+      window.removeEventListener('mousemove', dragObject, true);
+      window.removeEventListener('touchmove', dragObject, true);
     }
   }
 }
@@ -110,8 +110,8 @@ makeDragable('#shell_03header', '#shell_03')
   dragObj2.onmouseup = function(x) {
     if (dragObj2) {
       dragObj2 = null;
-      dragObj2.removeEventListener('mousemove', dragObject2, true);
-      dragObj2.removeEventListener('touchmove', dragObject2, true);
+      window.removeEventListener('mousemove', dragObject2, true);
+      window.removeEventListener('touchmove', dragObject2, true);
     }
   }
 }