diff --git a/cmd/restic/cmd_backup.go b/cmd/restic/cmd_backup.go
index 8a69f5cbf..c8b9154fb 100644
--- a/cmd/restic/cmd_backup.go
+++ b/cmd/restic/cmd_backup.go
@@ -83,7 +83,7 @@ func init() {
 	f.BoolVar(&backupOptions.Stdin, "stdin", false, "read backup from stdin")
 	f.StringVar(&backupOptions.StdinFilename, "stdin-filename", "stdin", "file name to use when reading from stdin")
 	f.StringArrayVar(&backupOptions.Tags, "tag", nil, "add a `tag` for the new snapshot (can be specified multiple times)")
-	f.StringVar(&backupOptions.Hostname, "hostname", "", "set the `hostname` for the snapshot manually")
+	f.StringVar(&backupOptions.Hostname, "hostname", "", "set the `hostname` for the snapshot manually. To prevent an expensive rescan use the \"parent\" flag")
 	f.StringVar(&backupOptions.FilesFrom, "files-from", "", "read the files to backup from file (can be combined with file args)")
 	f.StringVar(&backupOptions.TimeStamp, "time", "", "time of the backup (ex. '2012-11-01 22:08:41') (default: now)")
 }
diff --git a/doc/man/restic-backup.1 b/doc/man/restic-backup.1
index 7e255be47..742adc928 100644
--- a/doc/man/restic-backup.1
+++ b/doc/man/restic-backup.1
@@ -50,7 +50,7 @@ given as the arguments.
 
 .PP
 \fB\-\-hostname\fP=""
-    set the \fB\fChostname\fR for the snapshot manually
+    set the \fB\fChostname\fR for the snapshot manually. To prevent an expensive rescan use the "parent" flag
 
 .PP
 \fB\-x\fP, \fB\-\-one\-file\-system\fP[=false]