1 files changed, 11 insertions, 4 deletions
diff --git a/ractor.c b/ractor.c
index cce376c543..317b24dca2 100644
--- a/ractor.c
+++ b/ractor.c
@@ -1188,6 +1188,7 @@ obj_traverse_i(VALUE obj, struct obj_traverse_data *data)
         // already traversed
         return 0;
     }
+    RB_OBJ_WRITTEN(data->rec_hash, Qundef, obj);
 
     struct obj_traverse_callback_data d = {
         .stop = false,
@@ -1644,6 +1645,8 @@ obj_traverse_replace_i(VALUE obj, struct obj_traverse_replace_data *data)
     }
     else {
         st_insert(obj_traverse_replace_rec(data), (st_data_t)obj, replacement);
+        RB_OBJ_WRITTEN(data->rec_hash, Qundef, obj);
+        RB_OBJ_WRITTEN(data->rec_hash, Qundef, replacement);
     }
 
     if (!data->move) {
@@ -1657,8 +1660,8 @@ obj_traverse_replace_i(VALUE obj, struct obj_traverse_replace_data *data)
 } while (0)
 
     if (UNLIKELY(rb_obj_exivar_p(obj))) {
-        struct gen_fields_tbl *fields_tbl;
-        rb_ivar_generic_fields_tbl_lookup(obj, &fields_tbl);
+        VALUE fields_obj;
+        rb_ivar_generic_fields_tbl_lookup(obj, &fields_obj);
 
         if (UNLIKELY(rb_shape_obj_too_complex_p(obj))) {
             struct obj_traverse_replace_callback_data d = {
@@ -1667,7 +1670,7 @@ obj_traverse_replace_i(VALUE obj, struct obj_traverse_replace_data *data)
                 .src = obj,
             };
             rb_st_foreach_with_replace(
-                fields_tbl->as.complex.table,
+                rb_imemo_fields_complex_tbl(fields_obj),
                 obj_iv_hash_traverse_replace_foreach_i,
                 obj_iv_hash_traverse_replace_i,
                 (st_data_t)&d
@@ -1676,8 +1679,9 @@ obj_traverse_replace_i(VALUE obj, struct obj_traverse_replace_data *data)
         }
         else {
             uint32_t fields_count = RSHAPE_LEN(RBASIC_SHAPE_ID(obj));
+            VALUE *fields = rb_imemo_fields_ptr(fields_obj);
             for (uint32_t i = 0; i < fields_count; i++) {
-                CHECK_AND_REPLACE(fields_tbl->as.shape.fields[i]);
+                CHECK_AND_REPLACE(fields[i]);
             }
         }
     }
@@ -1881,6 +1885,9 @@ move_leave(VALUE obj, struct obj_traverse_replace_data *data)
         rb_gc_obj_slot_size(obj) - sizeof(VALUE)
     );
 
+    // We've copied obj's references to the replacement
+    rb_gc_writebarrier_remember(data->replacement);
+
     void rb_replace_generic_ivar(VALUE clone, VALUE obj); // variable.c
 
     rb_gc_obj_id_moved(data->replacement);