===================================================================
RCS file: /cvs/mandoc/mdoc_validate.c,v
retrieving revision 1.352
retrieving revision 1.353
diff -u -p -r1.352 -r1.353
--- mandoc/mdoc_validate.c	2017/08/02 13:29:04	1.352
+++ mandoc/mdoc_validate.c	2017/09/12 18:21:03	1.353
@@ -1,4 +1,4 @@
-/*	$Id: mdoc_validate.c,v 1.352 2017/08/02 13:29:04 schwarze Exp $ */
+/*	$Id: mdoc_validate.c,v 1.353 2017/09/12 18:21:03 schwarze Exp $ */
 /*
  * Copyright (c) 2008-2012 Kristaps Dzonsons <kristaps@bsd.lv>
  * Copyright (c) 2010-2017 Ingo Schwarze <schwarze@openbsd.org>
@@ -1914,7 +1914,10 @@ post_root(POST_ARGS)
 			arch++;
 		if (*arch == NULL) {
 			n = mdoc->first->child;
-			while (n->tok != MDOC_Dt)
+			while (n->tok != MDOC_Dt ||
+			    n->child == NULL ||
+			    n->child->next == NULL ||
+			    n->child->next->next == NULL)
 				n = n->next;
 			n = n->child->next->next;
 			mandoc_vmsg(MANDOCERR_ARCH_BAD,