Fix the placeholder subclass entry skipping [Bug #18489]

1 files changed, 1 insertions, 2 deletions

diff --git a/class.c b/class.c
index 9739aadc73..280ca8e97d 100644
--- a/class.c
+++ b/class.c
@@ -1054,8 +1054,7 @@ rb_include_module(VALUE klass, VALUE module)
     if (RB_TYPE_P(klass, T_MODULE)) {
         rb_subclass_entry_t *iclass = RCLASS_SUBCLASSES(klass);
         // skip the placeholder subclass entry at the head of the list
-        if (iclass && iclass->next) {
-            RUBY_ASSERT(!iclass->klass);
+        if (iclass && !iclass->klass) {
             iclass = iclass->next;
         }