diff --git a/vm.c b/vm.c
index 16524181be..10c9abc5b0 100644
--- a/vm.c
+++ b/vm.c
@@ -2368,6 +2368,7 @@ rb_thread_mark(void *ptr)
     rb_thread_t *th = ptr;
     RUBY_MARK_ENTER("thread");
 
+    /* mark VM stack */
     if (th->ec.stack) {
 	VALUE *p = th->ec.stack;
 	VALUE *sp = th->ec.cfp->sp;
@@ -2389,6 +2390,14 @@ rb_thread_mark(void *ptr)
 	}
     }
 
+    /* mark machine stack */
+    if (GET_THREAD() != th && th->machine.stack_start && th->machine.stack_end) {
+	rb_gc_mark_machine_stack(th);
+	rb_gc_mark_locations((VALUE *)&th->machine.regs,
+			     (VALUE *)(&th->machine.regs) +
+			     sizeof(th->machine.regs) / sizeof(VALUE));
+    }
+
     /* mark ruby objects */
     RUBY_MARK_UNLESS_NULL(th->first_proc);
     if (th->first_proc) RUBY_MARK_UNLESS_NULL(th->first_args);
@@ -2412,13 +2421,6 @@ rb_thread_mark(void *ptr)
     RUBY_MARK_UNLESS_NULL(th->local_storage_recursive_hash);
     RUBY_MARK_UNLESS_NULL(th->local_storage_recursive_hash_for_trace);
 
-    if (GET_THREAD() != th && th->machine.stack_start && th->machine.stack_end) {
-	rb_gc_mark_machine_stack(th);
-	rb_gc_mark_locations((VALUE *)&th->machine.regs,
-			     (VALUE *)(&th->machine.regs) +
-			     sizeof(th->machine.regs) / sizeof(VALUE));
-    }
-
     RUBY_MARK_UNLESS_NULL(th->name);
 
     rb_vm_trace_mark_event_hooks(&th->event_hooks);