===================================================================
RCS file: /cvs/mandoc/eqn_html.c,v
retrieving revision 1.16
retrieving revision 1.17
diff -u -p -r1.16 -r1.17
--- mandoc/eqn_html.c	2017/07/08 14:51:04	1.16
+++ mandoc/eqn_html.c	2017/07/14 13:32:35	1.17
@@ -1,4 +1,4 @@
-/*	$Id: eqn_html.c,v 1.16 2017/07/08 14:51:04 schwarze Exp $ */
+/*	$Id: eqn_html.c,v 1.17 2017/07/14 13:32:35 schwarze Exp $ */
 /*
  * Copyright (c) 2011, 2014 Kristaps Dzonsons <kristaps@bsd.lv>
  * Copyright (c) 2017 Ingo Schwarze <schwarze@openbsd.org>
@@ -230,6 +230,9 @@ void
 print_eqn(struct html *p, const struct eqn_box *bp)
 {
 	struct tag	*t;
+
+	if (bp->first == NULL)
+		return;
 
 	t = print_otag(p, TAG_MATH, "c", "eqn");