diff --git a/js/ui/windowManager.js b/js/ui/windowManager.js
index 8b5c46118..b1a3563ee 100644
--- a/js/ui/windowManager.js
+++ b/js/ui/windowManager.js
@@ -1346,9 +1346,10 @@ const WindowManager = new Lang.Class({
 
         let actorClone = actor.__fullscreenInfo.clone;
         let targetRect = actor.meta_window.get_frame_rect();
+        let sourceRect = actor.__fullscreenInfo.oldRect;
 
-        let scaleX = targetRect.width / actorClone.width;
-        let scaleY = targetRect.height / actorClone.height;
+        let scaleX = targetRect.width / sourceRect.width;
+        let scaleY = targetRect.height / sourceRect.height;
 
         this._resizing.push(actor);
 
@@ -1363,7 +1364,6 @@ const WindowManager = new Lang.Class({
                            transition: 'easeOutQuad'
                          });
 
-        let sourceRect = actor.__fullscreenInfo.oldRect;
         actor.translation_x = -targetRect.x + sourceRect.x;
         actor.translation_y = -targetRect.y + sourceRect.y;