===================================================================
RCS file: /cvs/mandoc/roff.c,v
retrieving revision 1.289
retrieving revision 1.290
diff -u -p -r1.289 -r1.290
--- mandoc/roff.c	2017/02/17 03:03:03	1.289
+++ mandoc/roff.c	2017/03/03 11:50:49	1.290
@@ -1,4 +1,4 @@
-/*	$Id: roff.c,v 1.289 2017/02/17 03:03:03 schwarze Exp $ */
+/*	$Id: roff.c,v 1.290 2017/03/03 11:50:49 schwarze Exp $ */
 /*
  * Copyright (c) 2008-2012, 2014 Kristaps Dzonsons <kristaps@bsd.lv>
  * Copyright (c) 2010-2015, 2017 Ingo Schwarze <schwarze@openbsd.org>
@@ -1236,7 +1236,7 @@ deroff(char **dest, const struct roff_node *n)
 	/* Skip trailing backslash. */
 
 	sz = strlen(cp);
-	if (cp[sz - 1] == '\\')
+	if (sz > 0 && cp[sz - 1] == '\\')
 		sz--;
 
 	/* Skip trailing whitespace. */