diff --git a/ChangeLog b/ChangeLog
index 9d8ddf63fd..04449febec 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,4 +1,6 @@
-Sat Jun 13 15:00:41 2009  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+Sat Jun 13 15:03:41 2009  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* load.c (load_lock): show backtrace at circular require.
 
 	* load.c (rb_provide): assumes us-ascii only.
 
diff --git a/load.c b/load.c
index f6d27ac6a3..2c59f33041 100644
--- a/load.c
+++ b/load.c
@@ -379,7 +379,10 @@ load_lock(const char *ftptr)
 	st_insert(loading_tbl, (st_data_t)ftptr, data);
 	return (char *)ftptr;
     }
-    rb_warning("loading in progress, circular require considered harmful - %s", ftptr);
+    if (RTEST(ruby_verbose)) {
+	rb_warning("loading in progress, circular require considered harmful - %s", ftptr);
+	rb_backtrace();
+    }
     return RTEST(rb_barrier_wait((VALUE)data)) ? (char *)ftptr : 0;
 }