===================================================================
RCS file: /cvsrepo/anoncvs/cvs/src/usr.bin/mandoc/tag.c,v
retrieving revision 1.20
retrieving revision 1.21
diff -c -r1.20 -r1.21
*** src/usr.bin/mandoc/tag.c	2018/10/23 20:41:59	1.20
--- src/usr.bin/mandoc/tag.c	2018/11/22 11:30:15	1.21
***************
*** 1,4 ****
! /*	$OpenBSD: tag.c,v 1.20 2018/10/23 20:41:59 schwarze Exp $ */
  /*
   * Copyright (c) 2015, 2016, 2018 Ingo Schwarze <schwarze@openbsd.org>
   *
--- 1,4 ----
! /*	$OpenBSD: tag.c,v 1.21 2018/11/22 11:30:15 schwarze Exp $ */
  /*
   * Copyright (c) 2015, 2016, 2018 Ingo Schwarze <schwarze@openbsd.org>
   *
***************
*** 16,21 ****
--- 16,22 ----
   */
  #include <sys/types.h>
  
+ #include <err.h>
  #include <limits.h>
  #include <signal.h>
  #include <stddef.h>
***************
*** 214,219 ****
--- 215,225 ----
  
  	if (tag_files.tfd <= 0)
  		return;
+ 	if (tag_files.tagname != NULL && ohash_find(&tag_data,
+             ohash_qlookup(&tag_data, tag_files.tagname)) == NULL) {
+ 		warnx("%s: no such tag", tag_files.tagname);
+ 		tag_files.tagname = NULL;
+ 	}
  	stream = fdopen(tag_files.tfd, "w");
  	entry = ohash_first(&tag_data, &slot);
  	while (entry != NULL) {