1 files changed, 2 insertions, 2 deletions
diff --git a/generic/tkBusy.c b/generic/tkBusy.c
index 32db4fc..82b4032 100644
--- a/generic/tkBusy.c
+++ b/generic/tkBusy.c
@@ -686,8 +686,8 @@ GetBusy(
     Tcl_HashEntry *hPtr;
     Tk_Window tkwin;
 
-    if (TkGetWindowFromObj(interp, Tk_MainWindow(interp), windowObj,
-	    &tkwin) != TCL_OK) {
+    tkwin = Tk_MainWindow(interp);
+    if (!tkwin || (TkGetWindowFromObj(interp, tkwin, windowObj, &tkwin) != TCL_OK)) {
 	return NULL;
     }
     hPtr = Tcl_FindHashEntry(busyTablePtr, (char *) tkwin);