From 06312377adc62ea1c82b5574749ee3704a1e4e9f Mon Sep 17 00:00:00 2001
From: Peter Zhu <peter@peterzhu.ca>
Date: Thu, 31 Jul 2025 14:38:16 -0400
Subject: [PATCH] Make Ractor::Selector write-barrier protected

---
 ractor_sync.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/ractor_sync.c b/ractor_sync.c
index a3ed38295b..057448c5f5 100644
--- a/ractor_sync.c
+++ b/ractor_sync.c
@@ -1273,7 +1273,7 @@ static const rb_data_type_t ractor_selector_data_type = {
         ractor_selector_memsize,
         NULL, // update
     },
-    0, 0, RUBY_TYPED_FREE_IMMEDIATELY,
+    0, 0, RUBY_TYPED_FREE_IMMEDIATELY | RUBY_TYPED_WB_PROTECTED,
 };
 
 static struct ractor_selector *
@@ -1318,6 +1318,8 @@ ractor_selector_add(VALUE selv, VALUE rpv)
     }
 
     st_insert(s->ports, (st_data_t)rpv, (st_data_t)rp);
+    RB_OBJ_WRITTEN(selv, Qundef, rpv);
+
     return selv;
 }