1 files changed, 1 insertions, 0 deletions
diff --git a/vm.c b/vm.c
index 665351be0a..2ab2b92fcc 100644
--- a/vm.c
+++ b/vm.c
@@ -1735,6 +1735,7 @@ rb_thread_mark(void *ptr)
 	RUBY_MARK_UNLESS_NULL(th->first_proc);
 	if (th->first_proc) RUBY_MARK_UNLESS_NULL(th->first_args);
 
+	RUBY_MARK_UNLESS_NULL(th->self);
 	RUBY_MARK_UNLESS_NULL(th->thgroup);
 	RUBY_MARK_UNLESS_NULL(th->value);
 	RUBY_MARK_UNLESS_NULL(th->errinfo);