===================================================================
RCS file: /cvs/mandoc/eqn_term.c,v
retrieving revision 1.8
retrieving revision 1.10
diff -u -p -r1.8 -r1.10
--- mandoc/eqn_term.c	2015/01/01 15:36:08	1.8
+++ mandoc/eqn_term.c	2017/07/05 15:03:27	1.10
@@ -1,7 +1,7 @@
-/*	$Id: eqn_term.c,v 1.8 2015/01/01 15:36:08 schwarze Exp $ */
+/*	$Id: eqn_term.c,v 1.10 2017/07/05 15:03:27 schwarze Exp $ */
 /*
  * Copyright (c) 2011 Kristaps Dzonsons <kristaps@bsd.lv>
- * Copyright (c) 2014, 2015 Ingo Schwarze <schwarze@openbsd.org>
+ * Copyright (c) 2014, 2015, 2017 Ingo Schwarze <schwarze@openbsd.org>
  *
  * Permission to use, copy, modify, and distribute this software for any
  * purpose with or without fee is hereby granted, provided that the above
@@ -52,7 +52,7 @@ eqn_box(struct termp *p, const struct eqn_box *bp)
 {
 	const struct eqn_box *child;
 
-	if (bp->type == EQN_LIST ||
+	if ((bp->type == EQN_LIST && bp->expectargs > 1) ||
 	    (bp->type == EQN_PILE && (bp->prev || bp->next)) ||
 	    (bp->parent != NULL && bp->parent->pos == EQNPOS_SQRT)) {
 		if (bp->parent->type == EQN_SUBEXPR && bp->prev != NULL)
@@ -68,8 +68,10 @@ eqn_box(struct termp *p, const struct eqn_box *bp)
 
 	if (bp->pos == EQNPOS_SQRT) {
 		term_word(p, "sqrt");
-		p->flags |= TERMP_NOSPACE;
-		eqn_box(p, bp->first);
+		if (bp->first != NULL) {
+			p->flags |= TERMP_NOSPACE;
+			eqn_box(p, bp->first);
+		}
 	} else if (bp->type == EQN_SUBEXPR) {
 		child = bp->first;
 		eqn_box(p, child);
@@ -93,12 +95,16 @@ eqn_box(struct termp *p, const struct eqn_box *bp)
 		}
 	} else {
 		child = bp->first;
-		if (bp->type == EQN_MATRIX && child->type == EQN_LIST)
+		if (bp->type == EQN_MATRIX &&
+		    child != NULL &&
+		    child->type == EQN_LIST &&
+		    child->expectargs > 1)
 			child = child->first;
 		while (child != NULL) {
 			eqn_box(p,
 			    bp->type == EQN_PILE &&
 			    child->type == EQN_LIST &&
+			    child->expectargs > 1 &&
 			    child->args == 1 ?
 			    child->first : child);
 			child = child->next;
@@ -107,7 +113,7 @@ eqn_box(struct termp *p, const struct eqn_box *bp)
 
 	if (bp->font != EQNFONT_NONE)
 		term_fontpop(p);
-	if (bp->type == EQN_LIST ||
+	if ((bp->type == EQN_LIST && bp->expectargs > 1) ||
 	    (bp->type == EQN_PILE && (bp->prev || bp->next)) ||
 	    (bp->parent != NULL && bp->parent->pos == EQNPOS_SQRT)) {
 		p->flags |= TERMP_NOSPACE;