diff --git a/Tools/idle/ZoomHeight.py b/Tools/idle/ZoomHeight.py
index b1ba70f0025..88bcee57539 100644
--- a/Tools/idle/ZoomHeight.py
+++ b/Tools/idle/ZoomHeight.py
@@ -32,7 +32,7 @@ def zoom_height_event(self, event):
         height = top.winfo_screenheight()
         if sys.platform == 'win32':
             y = 0
-            height = height = 72
+            height = height - 72
         else:
             y = 24
             height = height - 64