diff --git a/lib/mu-maildir.cc b/lib/mu-maildir.cc
index 4a0b2a73..f877c1a4 100644
--- a/lib/mu-maildir.cc
+++ b/lib/mu-maildir.cc
@@ -293,19 +293,8 @@ msg_move_g_file(const std::string& src, const std::string& dst)
 G_GNUC_UNUSED static Mu::Result<void>
 msg_move_mv_file(const std::string& src, const std::string& dst)
 {
-	const auto cmdline{mu_format("/bin/mv {} {}",
-				     to_string_gchar(g_shell_quote(src.c_str())),
-				     to_string_gchar(g_shell_quote(dst.c_str())))};
-	GError *err{};
-	int wait_status{};
-
-	mu_debug("{}", cmdline);
-
-	if (!g_spawn_command_line_sync(cmdline.c_str(), {}, {}, &wait_status, &err))
-		return Err(Error::Code::File, &err, "error moving {} -> {}", src, dst);
-	else if (auto&& res{WEXITSTATUS(wait_status)}; res != 0)
-		return Err(Error::Code::File, "error moving {} -> {}; err={}",
-			   src, dst, res);
+	if (auto res{run_command0({"/bin/mv", src, dst})}; !res)
+		return Err(Error::Code::File, "error moving {}->{}; err={}", src, dst, res.error());
 	else
 		return Ok();
 }
@@ -424,7 +413,7 @@ check_determine_target_params (const std::string& old_path,
 
 	if (any_of(newflags & Flags::New) && newflags != Flags::New)
 		return Err(Error{Error::Code::File,
-					"if ::New is specified, it must be the only flag"});
+					"if the New flag is specified, it must be the only flag"});
 	return Ok();
 }
 
@@ -436,6 +425,8 @@ Mu::maildir_determine_target(const std::string&	old_path,
 			     Flags		newflags,
 			     bool		new_name)
 {
+	newflags = flags_mail_dir_file(newflags); // filter out irrelevant flags.
+
 	/* sanity checks */
 	if (const auto checked{check_determine_target_params(
 		old_path, root_maildir_path, target_maildir, newflags)}; !checked)
diff --git a/lib/mu-maildir.hh b/lib/mu-maildir.hh
index 7aea17f7..93f12481 100644
--- a/lib/mu-maildir.hh
+++ b/lib/mu-maildir.hh
@@ -1,5 +1,5 @@
 /*
-** Copyright (C) 2008-2022 Dirk-Jan C. Binnema <djcb@djcbsoftware.nl>
+** Copyright (C) 2008-2023 Dirk-Jan C. Binnema <djcb@djcbsoftware.nl>
 **
 ** This program is free software; you can redistribute it and/or modify it
 ** under the terms of the GNU General Public License as published by the
@@ -97,19 +97,18 @@ Result<void> maildir_move_message(const std::string& oldpath,
  * @param old_path an absolute file system path to an existing message in an
  * actual maildir
  * @param root_maildir_path the absolete file system path under which
- * all maidlirs live.
+ * all maildirs live.
  * @param target_maildir the target maildir; note that this the base-level
  * Maildir, ie. /home/user/Maildir/archive, and must _not_ include the
  * 'cur' or 'new' part. Note that the target maildir must be on the
  * same filesystem. Can be empty if the message should not be moved to
  * a different maildir; note that this may still involve a
  * move to another directory (say, from new/ to cur/)
- * @param flags to set for the target (influences the filename, path).
+ * @param flags to set for the target (influences the filename, path). Any none-Maildir/File
+ * flags are ignored.
  * @param new_name whether to change the basename of the file
- * @param err receives error information
  *
- * @return Full path name of the target file or std::nullopt in case
- * of error
+ * @return Full path name of the target file or an Error
  */
 Result<std::string>
 maildir_determine_target(const std::string&	old_path,