diff --git a/bootstraptest/test_thread.rb b/bootstraptest/test_thread.rb
index 02cd2029aa..54544df45e 100644
--- a/bootstraptest/test_thread.rb
+++ b/bootstraptest/test_thread.rb
@@ -224,7 +224,7 @@ assert_equal 'ok', %{
         pid, status = Process.wait2
         $result = status.success? ? :ok : :ng
       rescue NotImplementedError
-        :ok
+        $result = :ok
       end
     END
   end