1 files changed, 4 insertions, 0 deletions
diff --git a/vm.c b/vm.c
index ad687d579a..73d6cd9d5d 100644
--- a/vm.c
+++ b/vm.c
@@ -1181,6 +1181,10 @@ rb_proc_ractor_make_shareable(VALUE self)
         rb_proc_t *proc = (rb_proc_t *)RTYPEDDATA_DATA(self);
         if (proc->block.type != block_type_iseq) rb_raise(rb_eRuntimeError, "not supported yet");
 
+        if (!rb_ractor_shareable_p(vm_block_self(&proc->block))) {
+            rb_raise(rb_eRactorIsolationError, "Proc's self is not shareable");
+        }
+
         VALUE read_only_variables = Qfalse;
 
         if (iseq->body->outer_variables) {