1 files changed, 3 insertions, 0 deletions
diff --git a/thread.c b/thread.c
index babec1f51e..eaf408fa6d 100644
--- a/thread.c
+++ b/thread.c
@@ -4562,6 +4562,9 @@ rb_mutex_sleep(VALUE self, VALUE timeout)
  * non-nil or forever.  Raises +ThreadError+ if +mutex+ wasn't locked by
  * the current thread.
  *
+ * When the thread is next woken up, it will attempt to reacquire
+ * the lock.
+ *
  * Note that this method can wakeup without explicit Thread#wakeup call.
  * For example, receiving signal and so on.
  */