--- ./doc/Makefile.in.orig	2013-07-15 14:59:04.840695596 +0000
+++ ./doc/Makefile.in	2013-07-15 14:59:30.667643646 +0000
@@ -379,13 +379,13 @@
 
 
 .xml.html:
-	xmlto xhtml-nochunks $<
+	xmlto --skip-validation xhtml-nochunks $<
 
 .xml.1:
-	xmlto man $<
+	xmlto --skip-validation man $<
 
 .xml.txt:
-	xmlto txt $<
+	xmlto --skip-validation txt $<
 
 all: allhtml manpages