diff --git a/usr.bin/sort/files.c b/usr.bin/sort/files.c
index b36f6945a8ce..7cb27c5385a3 100644
--- a/usr.bin/sort/files.c
+++ b/usr.bin/sort/files.c
@@ -1,4 +1,4 @@
-/*	$NetBSD: files.c,v 1.41 2009/11/06 18:34:22 joerg Exp $	*/
+/*	$NetBSD: files.c,v 1.42 2015/08/05 07:10:03 mrg Exp $	*/
 
 /*-
  * Copyright (c) 2000-2003 The NetBSD Foundation, Inc.
@@ -64,7 +64,7 @@
 #include "sort.h"
 #include "fsort.h"
 
-__RCSID("$NetBSD: files.c,v 1.41 2009/11/06 18:34:22 joerg Exp $");
+__RCSID("$NetBSD: files.c,v 1.42 2015/08/05 07:10:03 mrg Exp $");
 
 #include <string.h>
 
@@ -226,7 +226,8 @@ seq(FILE *fp, u_char **line)
 void
 putrec(const RECHEADER *rec, FILE *fp)
 {
-	EWRITE(rec, 1, REC_ROUNDUP(offsetof(RECHEADER, data) + rec->length), fp);
+	EWRITE(rec, 1, REC_ROUNDUP(offsetof(RECHEADER, data) + rec->length), fp,
+	       "failed to write temp file");
 }
 
 /*
@@ -235,7 +236,8 @@ putrec(const RECHEADER *rec, FILE *fp)
 void
 putline(const RECHEADER *rec, FILE *fp)
 {
-	EWRITE(rec->data+rec->offset, 1, rec->length - rec->offset, fp);
+	EWRITE(rec->data+rec->offset, 1, rec->length - rec->offset, fp,
+	       "failed to write");
 }
 
 /*
@@ -244,7 +246,8 @@ putline(const RECHEADER *rec, FILE *fp)
 void
 putkeydump(const RECHEADER *rec, FILE *fp)
 {
-	EWRITE(rec, 1, REC_ROUNDUP(offsetof(RECHEADER, data) + rec->offset), fp);
+	EWRITE(rec, 1, REC_ROUNDUP(offsetof(RECHEADER, data) + rec->offset), fp,
+	       "failed to write debug key");
 }
 
 /*
diff --git a/usr.bin/sort/sort.h b/usr.bin/sort/sort.h
index 677fd452265c..d34134d4c9a3 100644
--- a/usr.bin/sort/sort.h
+++ b/usr.bin/sort/sort.h
@@ -1,4 +1,4 @@
-/*	$NetBSD: sort.h,v 1.34 2011/09/16 15:39:29 joerg Exp $	*/
+/*	$NetBSD: sort.h,v 1.35 2015/08/05 07:10:03 mrg Exp $	*/
 
 /*-
  * Copyright (c) 2000-2003 The NetBSD Foundation, Inc.
@@ -100,9 +100,9 @@
 		err(2, "%p", file);					\
 }
 
-#define	EWRITE(ptr, size, n, f) {					\
+#define	EWRITE(ptr, size, n, f, fmt) {					\
 	if (!fwrite(ptr, size, n, f))					\
-		 err(2, NULL);						\
+		 err(2, fmt);						\
 }
 
 /* Records are limited to MAXBUFSIZE (8MB) and less if you want to sort