diff --git a/lib/X11/form.rb b/lib/X11/form.rb
index 5516941..90b3405 100644
--- a/lib/X11/form.rb
+++ b/lib/X11/form.rb
@@ -1,3 +1,5 @@
+require 'ostruct'
+
 module X11
   module Form
     # A form object is an X11 packet definition. We use forms to encode