diff --git a/ChangeLog b/ChangeLog
index 6d7b77a277..30fd4c338e 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Tue Aug 31 12:30:36 2004  Hidetoshi NAGAI  <nagai@ai.kyutech.ac.jp>
+
+	* ext/tcltklib/tcltklib.c (del_root): fix SEGV
+
 Mon Aug 30 23:11:06 2004  Dave Thomas  <dave@pragprog.com>
 
 	* lib/rdoc/ri/ri_driver.rb (and others): ri now merges documentation
diff --git a/ext/tcltklib/tcltklib.c b/ext/tcltklib/tcltklib.c
index 0217ab8feb..84a999d7e4 100644
--- a/ext/tcltklib/tcltklib.c
+++ b/ext/tcltklib/tcltklib.c
@@ -2781,8 +2781,13 @@ ip_thread_tkwait(self, mode, target)
 VALUE del_root(ip)
     Tcl_Interp *ip;
 {
+    Tk_Window main_win;
+
     Tcl_Preserve(ip);
-    Tk_DestroyWindow(Tk_MainWindow(ip));
+    main_win = Tk_MainWindow(ip);
+    if (main_win != (Tk_Window)NULL) {
+	Tk_DestroyWindow(main_win);
+    }
     Tcl_Release(ip);
     return Qnil;
 }