diff --git a/ChangeLog b/ChangeLog
index 0a9db443a9..6e49270ad3 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Mon Jul 28 18:58:46 2008  Yusuke Endoh  <mame@tsg.ne.jp>
+
+	* thread.c (mutex_unlock): fix typo.
+
 Mon Jul 28 18:15:45 2008  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* file.c (rb_find_file_ext, rb_find_file): not to split load path with
diff --git a/thread.c b/thread.c
index 0a313abe13..c965a657de 100644
--- a/thread.c
+++ b/thread.c
@@ -2741,7 +2741,7 @@ mutex_unlock(mutex_t *mutex)
 		th_mutex = tmp_mutex;
 	    }
 	}
-	mutex->next_mutex = Qfalse;
+	mutex->next_mutex = NULL;
     }
 
     return err;