diff --git a/lib/ostruct.rb b/lib/ostruct.rb
index a8763da..1ca8553 100644
--- a/lib/ostruct.rb
+++ b/lib/ostruct.rb
@@ -254,6 +254,8 @@ def new_ostruct_member!(name) # :nodoc:
   private def is_method_protected!(name) # :nodoc:
     if !respond_to?(name, true)
       false
+    elsif name.match?(/^object_id$/)
+      true
     elsif name.match?(/!$/)
       true
     else