diff --git a/js/rpg_core/WindowLayer.js b/js/rpg_core/WindowLayer.js
index 02d3f432..26e1acc7 100644
--- a/js/rpg_core/WindowLayer.js
+++ b/js/rpg_core/WindowLayer.js
@@ -227,7 +227,7 @@ WindowLayer.prototype._maskWindow = function(window, shift) {
     this._windowMask.boundsDirty = true;
     var rect = this._windowRect;
     rect.x = this.x + shift.x + window.x;
-    rect.y = this.x + shift.y + window.y + window.height / 2 * (1 - window._openness / 255);
+    rect.y = this.y + shift.y + window.y + window.height / 2 * (1 - window._openness / 255);
     rect.width = window.width;
     rect.height = window.height * window._openness / 255;
 };