diff -Nurd -x'*~' rubyosa-0.4.0.orig/src/rbosa.c rubyosa-0.4.0/src/rbosa.c
--- rubyosa-0.4.0.orig/src/rbosa.c	2007-04-11 17:16:57.000000000 -0400
+++ rubyosa-0.4.0/src/rbosa.c	2012-02-06 08:08:45.000000000 -0500
@@ -26,6 +26,7 @@
  * POSSIBILITY OF SUCH DAMAGE.
  */ 
 
+#include <ruby.h>
 #include "rbosa.h"
 #include <st.h>