Index: subversion/libsvn_subr/checksum.c
===================================================================
--- subversion/libsvn_subr/checksum.c	(revision 32534)
+++ subversion/libsvn_subr/checksum.c	(working copy)
@@ -17,6 +17,8 @@
  */
 
 
+#include <ctype.h>
+
 #include "svn_checksum.h"
 #include "svn_md5.h"
 #include "svn_sha1.h"