--- rdoff/rdx.c
+++ rdoff/rdx.c
@@ -51,7 +51,7 @@
         exit(255);
     }
 
-    code = (main_fn) s->offset;
+    code = (main_fn) (intptr_t) s->offset;
 
     argv++, argc--;             /* remove 'rdx' from command line */