1 files changed, 1 insertions, 0 deletions
diff --git a/vm.c b/vm.c
index 9114ba456c..1e1c06e0e2 100644
--- a/vm.c
+++ b/vm.c
@@ -3052,6 +3052,7 @@ th_init(rb_thread_t *th, VALUE self)
 #endif
     th->name = Qnil;
     th->report_on_exception = th->vm->thread_report_on_exception;
+    th->ext_config.ractor_safe = true;
 }
 
 static VALUE