1 files changed, 1 insertions, 2 deletions

diff --git a/vm.c b/vm.c
index 5cc4658290..6636a52258 100644
--- a/vm.c
+++ b/vm.c
@@ -1478,7 +1478,7 @@ thread_free(void *ptr)
 	if (th->locking_mutex != Qfalse) {
 	    rb_bug("thread_free: locking_mutex must be NULL (%p:%ld)", th, th->locking_mutex);
 	}
-	if (th->keeping_mutexes != Qfalse) {
+	if (th->keeping_mutexes != NULL) {
 	    rb_bug("thread_free: keeping_mutexes must be NULL (%p:%ld)", th, th->locking_mutex);
 	}
 
@@ -1551,7 +1551,6 @@ rb_thread_mark(void *ptr)
 	RUBY_MARK_UNLESS_NULL(th->last_status);
 
 	RUBY_MARK_UNLESS_NULL(th->locking_mutex);
-	RUBY_MARK_UNLESS_NULL(th->keeping_mutexes);
 
 	rb_mark_tbl(th->local_storage);