diff --git a/ba/ba0102.cpp b/ba/ba0102.cpp
index af0f28643..d3ec13f74 100755
--- a/ba/ba0102.cpp
+++ b/ba/ba0102.cpp
@@ -1061,8 +1061,11 @@ bool TSpidey_mask::stop_run(KEY k)
       {
         if (!yesno_box(TR("Si desidera uscire?")))  //..altrimenti chiede educatamente se si desidera uscire
         {
-          for (i = 3; i >= 0; i--)
-            xvt_dwin_invalidate_rect(window[i], NULL);
+          for (i = 0; i < 3; i++)
+          {
+            if (window[i] != NULL)
+              xvt_dwin_invalidate_rect(window[i], NULL);
+          }
           return false;
         }
       }