diff -Naur bison-2.5-orig/lib/yyerror.c bison-2.5/lib/yyerror.c
--- bison-2.5-orig/lib/yyerror.c	2011-01-04 00:50:42.000000000 +1000
+++ bison-2.5/lib/yyerror.c	2011-11-09 22:01:48.725507079 +1000
@@ -18,6 +18,7 @@
    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
 
 #include <stdio.h>
+#undef fprintf
 
 int yyerror (char const *);