diff --git a/src/osx/cocoa/window.mm b/src/osx/cocoa/window.mm
index d5865bfdc4..4e0e77f95b 100644
--- a/src/osx/cocoa/window.mm
+++ b/src/osx/cocoa/window.mm
@@ -1146,7 +1146,7 @@ void wxWidgetCocoaImpl::drawRect(void* rect, WXWidget slf, void *WXUNUSED(_cmd))
 #if OSX_DEBUG_DRAWING
     CGContextBeginPath( context );
     CGContextMoveToPoint(context, 0, 0);
-    NSRect bounds = [self bounds];
+    NSRect bounds = [slf bounds];
     CGContextAddLineToPoint(context, 10, 0);
     CGContextMoveToPoint(context, 0, 0);
     CGContextAddLineToPoint(context, 0, 10);