diff --git a/ChangeLog b/ChangeLog
index e503f70d54..16e605e38d 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Fri Feb 12 17:55:21 2010  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* vm.c (thread_free): fixed typo.
+
 Fri Feb 12 02:27:39 2010  Akinori MUSHA  <knu@iDaemons.org>
 
 	* lib/set.rb (Set#initialize, Set#replace, Set#merge)
diff --git a/vm.c b/vm.c
index e963225ae8..fc58d07c6d 100644
--- a/vm.c
+++ b/vm.c
@@ -1681,7 +1681,7 @@ thread_free(void *ptr)
 	    rb_bug("thread_free: locking_mutex must be NULL (%p:%ld)", (void *)th, th->locking_mutex);
 	}
 	if (th->keeping_mutexes != NULL) {
-	    rb_bug("thread_free: keeping_mutexes must be NULL (%p:%ld)", (void *)th, th->locking_mutex);
+	    rb_bug("thread_free: keeping_mutexes must be NULL (%p:%p)", (void *)th, th->keeping_mutexes);
 	}
 
 	if (th->local_storage) {