1 files changed, 1 insertions, 0 deletions
diff --git a/gc.c b/gc.c
index c59c73696b..8840771c2f 100644
--- a/gc.c
+++ b/gc.c
@@ -1824,6 +1824,7 @@ gc_mark_children(rb_objspace_t *objspace, VALUE ptr, int lev)
       case T_CLASS:
       case T_MODULE:
 	mark_m_tbl(objspace, RCLASS_M_TBL(obj), lev);
+	if (!RCLASS_EXT(obj)) break;
 	mark_tbl(objspace, RCLASS_IV_TBL(obj), lev);
 	mark_const_tbl(objspace, RCLASS_CONST_TBL(obj), lev);
 	ptr = RCLASS_SUPER(obj);