diff --git a/src/Fl_cocoa.mm b/src/Fl_cocoa.mm
index 77f7c1085..06f801e64 100644
--- a/src/Fl_cocoa.mm
+++ b/src/Fl_cocoa.mm
@@ -1929,6 +1929,7 @@ static void cocoaKeyboardHandler(NSEvent *theEvent)
 - (void)resetCursorRects {
   Fl_Window *w = [(FLWindow*)[self window] getFl_Window];
   Fl_X *i = Fl_X::i(w);
+  if (!i) return;  // fix for STR #3128
   // We have to have at least one cursor rect for invalidateCursorRectsForView
   // to work, hence the "else" clause.
   if (i->cursor)