diff --git a/src/viewport.cpp b/src/viewport.cpp
index 1ecfb42e70..f8d78f5c64 100644
--- a/src/viewport.cpp
+++ b/src/viewport.cpp
@@ -388,8 +388,8 @@ void InitializeWindowViewport(Window *w, int x, int y,
 
 	vp->virtual_left = 0;
 	vp->virtual_top = 0;
-	vp->virtual_width = ScaleByZoom(width, zoom);
-	vp->virtual_height = ScaleByZoom(height, zoom);
+	vp->virtual_width = ScaleByZoom(width, vp->zoom);
+	vp->virtual_height = ScaleByZoom(height, vp->zoom);
 
 	vp->map_type = VPMT_BEGIN;