1 files changed, 1 insertions, 0 deletions
diff --git a/thread.c b/thread.c
index 9f2267a1f4..fad0ce6efc 100644
--- a/thread.c
+++ b/thread.c
@@ -4208,6 +4208,7 @@ rb_thread_atfork(void)
     rb_thread_t *th = GET_THREAD();
     rb_thread_atfork_internal(th, terminate_atfork_i);
     th->join_list = NULL;
+    rb_mutex_cleanup_keeping_mutexes(th);
 
     /* We don't want reproduce CVE-2003-0900. */
     rb_reset_random_seed();