diff --git a/lib/json/generic_object.rb b/lib/json/generic_object.rb
index b7b8b04e..56efda64 100644
--- a/lib/json/generic_object.rb
+++ b/lib/json/generic_object.rb
@@ -2,6 +2,7 @@
 begin
   require 'ostruct'
 rescue LoadError
+  warn "JSON::GenericObject requires 'ostruct'. Please install it with `gem install ostruct`."
 end
 
 module JSON