1 files changed, 1 insertions, 0 deletions
diff --git a/class.c b/class.c
index 4c469ffaeb..b7247e7489 100644
--- a/class.c
+++ b/class.c
@@ -1435,6 +1435,7 @@ method_entry_i(ID key, VALUE value, void *data)
 	}
 	else {
 	    type = METHOD_ENTRY_VISI(me);
+	    RUBY_ASSERT(type != METHOD_VISI_UNDEF);
 	}
 	st_add_direct(arg->list, key, (st_data_t)type);
     }