===================================================================
RCS file: /cvs/mandoc/eqn_html.c,v
retrieving revision 1.15
retrieving revision 1.17
diff -u -p -r1.15 -r1.17
--- mandoc/eqn_html.c	2017/07/05 15:03:27	1.15
+++ mandoc/eqn_html.c	2017/07/14 13:32:35	1.17
@@ -1,4 +1,4 @@
-/*	$Id: eqn_html.c,v 1.15 2017/07/05 15:03:27 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>
@@ -227,14 +227,17 @@ out:
 }
 
 void
-print_eqn(struct html *p, const struct eqn *ep)
+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");
 
 	p->flags |= HTML_NONOSPACE;
-	eqn_box(p, ep->root);
+	eqn_box(p, bp);
 	p->flags &= ~HTML_NONOSPACE;
 
 	print_tagq(p, t);