--- a\src\win\iupwin_filedlg.c	Mon Dec 11 14:52:42 2017
+++ b\src\win\iupwin_filedlg.c	Wed Jan 24 22:56:29 2018
@@ -548,7 +548,10 @@
       Ihandle* ih = (Ihandle*)GetWindowLongPtr(hWnd, DWLP_USER);
       /* callback here always exists */
       IFnss cb = (IFnss)IupGetCallback(ih, "FILE_CB");
-      cb(ih, NULL, "FINISH");
+      if (cb)
+      {
+        cb(ih, NULL, "FINISH");
+      }
       break;
     }
   case WM_XBUTTONDBLCLK: