From 903c5f978a2966465d8d5c6dfac55a977d134287 Mon Sep 17 00:00:00 2001
From: "Yukihiro \"Matz\" Matsumoto" <matz@ruby.or.jp>
Date: Thu, 3 Feb 2022 10:41:09 +0900
Subject: [PATCH] vm.c: check object type before concatenating strings.

---
 src/vm.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/vm.c b/src/vm.c
index b0cd9428d..cc53c0bb5 100644
--- a/src/vm.c
+++ b/src/vm.c
@@ -2756,6 +2756,7 @@ RETRY_TRY_BLOCK:
     }
 
     CASE(OP_STRCAT, B) {
+      mrb_ensure_string_type(mrb, regs[a]);
       mrb_str_concat(mrb, regs[a], regs[a+1]);
       NEXT;
     }