diff --git a/AppKit/CPBox.j b/AppKit/CPBox.j
index a8d7ef2a1..2eedd0768 100644
--- a/AppKit/CPBox.j
+++ b/AppKit/CPBox.j
@@ -104,7 +104,7 @@ CPGrooveBorder  = 3;
     if (_borderType === aBorderType)
         return;
 
-    _borderType = value;
+    _borderType = aBorderType;
     [self setNeedsDisplay:YES];
 }