diff --git a/lib/argp-help.c b/lib/argp-help.c
index 4c0ca60..5ca3378 100644
--- a/lib/argp-help.c
+++ b/lib/argp-help.c
@@ -46,6 +46,16 @@
 # include "gettext.h"
 #endif
 
+#ifdef _LIBC
+# define ARGP_TEXT_DOMAIN "libc"
+#else
+# ifdef DEFAULT_TEXT_DOMAIN
+#  define ARGP_TEXT_DOMAIN DEFAULT_TEXT_DOMAIN
+# else
+#  define ARGP_TEXT_DOMAIN NULL
+# endif
+#endif
+
 #include "argp.h"
 #include "argp-fmtstream.h"
 #include "argp-namefrob.h"
@@ -143,7 +153,7 @@ validate_uparams (const struct argp_state *state, struct uparams *upptr)
       if (*(int *)((char *)upptr + up->uparams_offs) >= upptr->rmargin)
 	{
 	  __argp_failure (state, 0, 0,
-			  dgettext (state->root_argp->argp_domain,
+			  dgettext (ARGP_TEXT_DOMAIN,
 				    "\
 ARGP_HELP_FMT: %s value is less than or equal to %s"),
 			  "rmargin", up->name);
@@ -216,13 +226,13 @@ fill_in_uparams (const struct argp_state *state)
 		  {
 		    if (unspec && !un->is_bool)
 		      __argp_failure (state, 0, 0,
-				      dgettext (state->root_argp->argp_domain,
+				      dgettext (ARGP_TEXT_DOMAIN,
 						"\
 %.*s: ARGP_HELP_FMT parameter requires a value"),
 				      (int) var_len, var);
 		    else if (val < 0)
 		      __argp_failure (state, 0, 0,
-				      dgettext (state->root_argp->argp_domain,
+				      dgettext (ARGP_TEXT_DOMAIN,
 						"\
 %.*s: ARGP_HELP_FMT parameter must be positive"),
 				      (int) var_len, var);
@@ -232,7 +242,7 @@ fill_in_uparams (const struct argp_state *state)
 		  }
 	      if (! un->name)
 		__argp_failure (state, 0, 0,
-				dgettext (state->root_argp->argp_domain, "\
+				dgettext (ARGP_TEXT_DOMAIN, "\
 %.*s: Unknown ARGP_HELP_FMT parameter"),
 				(int) var_len, var);
 
@@ -243,7 +253,7 @@ fill_in_uparams (const struct argp_state *state)
 	  else if (*var)
 	    {
 	      __argp_failure (state, 0, 0,
-			      dgettext (state->root_argp->argp_domain,
+			      dgettext (ARGP_TEXT_DOMAIN,
 					"Garbage in ARGP_HELP_FMT: %s"), var);
 	      break;
 	    }
@@ -1135,7 +1145,7 @@ hol_entry_help (struct hol_entry *entry, const struct argp_state *state,
 	    __argp_fmtstream_putc (stream, '-');
 	    __argp_fmtstream_putc (stream, *so);
 	    if (!have_long_opt || uparams.dup_args)
-	      arg (real, " %s", "[%s]", state->root_argp->argp_domain, stream);
+	      arg (real, " %s", "[%s]", entry->argp->argp_domain, stream);
 	    else if (real->arg)
 	      hhstate->suppressed_dup_arg = 1;
 	  }
@@ -1157,7 +1167,7 @@ hol_entry_help (struct hol_entry *entry, const struct argp_state *state,
 	    __argp_fmtstream_puts (stream,
 				   onotrans (opt) ?
 				             opt->name :
-				   dgettext (state->root_argp->argp_domain,
+				   dgettext (entry->argp->argp_domain,
 					     opt->name));
 	  }
     }
@@ -1173,7 +1183,7 @@ hol_entry_help (struct hol_entry *entry, const struct argp_state *state,
 	    comma (uparams.long_opt_col, &pest);
 	    __argp_fmtstream_printf (stream, "--%s", opt->name);
 	    if (first_long_opt || uparams.dup_args)
-	      arg (real, "=%s", "[=%s]", state->root_argp->argp_domain,
+	      arg (real, "=%s", "[=%s]", entry->argp->argp_domain,
 		   stream);
 	    else if (real->arg)
 	      hhstate->suppressed_dup_arg = 1;
@@ -1195,7 +1205,7 @@ hol_entry_help (struct hol_entry *entry, const struct argp_state *state,
     }
   else
     {
-      const char *tstr = real->doc ? dgettext (state->root_argp->argp_domain,
+      const char *tstr = real->doc ? dgettext (entry->argp->argp_domain,
 					       real->doc) : 0;
       const char *fstr = filter_doc (tstr, real->key, entry->argp, state);
       if (fstr && *fstr)
@@ -1243,7 +1253,7 @@ hol_help (struct hol *hol, const struct argp_state *state,
 
   if (hhstate.suppressed_dup_arg && uparams.dup_args_note)
     {
-      const char *tstr = dgettext (state->root_argp->argp_domain, "\
+      const char *tstr = dgettext (ARGP_TEXT_DOMAIN, "\
 Mandatory or optional arguments to long options are also mandatory or \
 optional for any corresponding short options.");
       const char *fstr = filter_doc (tstr, ARGP_KEY_HELP_DUP_ARGS_NOTE,
@@ -1636,11 +1646,11 @@ _help (const struct argp *argp, const struct argp_state *state, FILE *stream,
 
 	  if (first_pattern)
 	    __argp_fmtstream_printf (fs, "%s %s",
-				     dgettext (argp->argp_domain, "Usage:"),
+				     dgettext (ARGP_TEXT_DOMAIN, "Usage:"),
 				     name);
 	  else
 	    __argp_fmtstream_printf (fs, "%s %s",
-				     dgettext (argp->argp_domain, "  or: "),
+				     dgettext (ARGP_TEXT_DOMAIN, "  or: "),
 				     name);
 
 	  /* We set the lmargin as well as the wmargin, because hol_usage
@@ -1651,7 +1661,7 @@ _help (const struct argp *argp, const struct argp_state *state, FILE *stream,
 	    /* Just show where the options go.  */
 	    {
 	      if (hol->num_entries > 0)
-		__argp_fmtstream_puts (fs, dgettext (argp->argp_domain,
+		__argp_fmtstream_puts (fs, dgettext (ARGP_TEXT_DOMAIN,
 						     " [OPTION...]"));
 	    }
 	  else
@@ -1679,7 +1689,7 @@ _help (const struct argp *argp, const struct argp_state *state, FILE *stream,
 
   if (flags & ARGP_HELP_SEE)
     {
-      __argp_fmtstream_printf (fs, dgettext (argp->argp_domain, "\
+      __argp_fmtstream_printf (fs, dgettext (ARGP_TEXT_DOMAIN, "\
 Try `%s --help' or `%s --usage' for more information.\n"),
 			       name, name);
       anything = 1;
@@ -1706,7 +1716,7 @@ Try `%s --help' or `%s --usage' for more information.\n"),
     {
       if (anything)
 	__argp_fmtstream_putc (fs, '\n');
-      __argp_fmtstream_printf (fs, dgettext (argp->argp_domain,
+      __argp_fmtstream_printf (fs, dgettext (ARGP_TEXT_DOMAIN,
 					     "Report bugs to %s.\n"),
  			       argp_program_bug_address);
       anything = 1;
@@ -1925,8 +1935,7 @@ __argp_failure (const struct argp_state *state, int status, int errnum,
 #endif
 #if !_LIBC
 		  if (! s && ! (s = strerror (errnum)))
-		    s = dgettext (state->root_argp->argp_domain,
-				  "Unknown system error");
+		    s = dgettext (ARGP_TEXT_DOMAIN, "Unknown system error");
 #endif
 		  fputs (s, stream);
 		}
diff --git a/lib/argp-parse.c b/lib/argp-parse.c
index d86256a..bd0fa4e 100644
--- a/lib/argp-parse.c
+++ b/lib/argp-parse.c
@@ -39,6 +39,16 @@
 #endif
 #define N_(msgid) msgid
 
+#ifdef _LIBC
+# define ARGP_TEXT_DOMAIN "libc"
+#else
+# ifdef DEFAULT_TEXT_DOMAIN
+#  define ARGP_TEXT_DOMAIN DEFAULT_TEXT_DOMAIN
+# else
+#  define ARGP_TEXT_DOMAIN NULL
+# endif
+#endif
+
 #include "argp.h"
 #include "argp-namefrob.h"
 
@@ -134,7 +144,8 @@ argp_default_parser (int key, char *arg, struct argp_state *state)
 }
 
 static const struct argp argp_default_argp =
-  {argp_default_options, &argp_default_parser, NULL, NULL, NULL, NULL, "libc"};
+  {argp_default_options, &argp_default_parser, NULL, NULL, NULL, NULL,
+   ARGP_TEXT_DOMAIN};
 
 
 static const struct argp_option argp_version_options[] =
@@ -154,7 +165,7 @@ argp_version_parser (int key, char *arg, struct argp_state *state)
       else if (argp_program_version)
 	fprintf (state->out_stream, "%s\n", argp_program_version);
       else
-	__argp_error (state, dgettext (state->root_argp->argp_domain,
+	__argp_error (state, dgettext (ARGP_TEXT_DOMAIN,
 				       "(PROGRAM ERROR) No version known!?"));
       if (! (state->flags & ARGP_NO_EXIT))
 	exit (0);
@@ -166,7 +177,8 @@ argp_version_parser (int key, char *arg, struct argp_state *state)
 }
 
 static const struct argp argp_version_argp =
-  {argp_version_options, &argp_version_parser, NULL, NULL, NULL, NULL, "libc"};
+  {argp_version_options, &argp_version_parser, NULL, NULL, NULL, NULL,
+   ARGP_TEXT_DOMAIN};
 
 /* Returns the offset into the getopt long options array LONG_OPTIONS of a
    long option with called NAME, or -1 if none is found.  Passing NULL as
@@ -607,8 +619,7 @@ parser_finalize (struct parser *parser,
 	  if (!(parser->state.flags & ARGP_NO_ERRS)
 	      && parser->state.err_stream)
 	    fprintf (parser->state.err_stream,
-		     dgettext (parser->argp->argp_domain,
-			       "%s: Too many arguments\n"),
+		     dgettext (ARGP_TEXT_DOMAIN, "%s: Too many arguments\n"),
 		     parser->state.name);
 	  err = EBADKEY;
 	}
@@ -754,7 +765,7 @@ parser_parse_opt (struct parser *parser, int opt, char *val)
 	N_("(PROGRAM ERROR) Option should have been recognized!?");
       if (group_key == 0)
 	__argp_error (&parser->state, "-%c: %s", opt,
-		      dgettext (parser->argp->argp_domain, bad_key_err));
+		      dgettext (ARGP_TEXT_DOMAIN, bad_key_err));
       else
 	{
 	  struct option *long_opt = parser->long_opts;
@@ -762,7 +773,7 @@ parser_parse_opt (struct parser *parser, int opt, char *val)
 	    long_opt++;
 	  __argp_error (&parser->state, "--%s: %s",
 			long_opt->name ? long_opt->name : "???",
-			dgettext (parser->argp->argp_domain, bad_key_err));
+			dgettext (ARGP_TEXT_DOMAIN, bad_key_err));
 	}
     }