diff --git a/weed/command/export.go b/weed/command/export.go
index 481aa111b..5a7dc71d9 100644
--- a/weed/command/export.go
+++ b/weed/command/export.go
@@ -51,7 +51,7 @@ func init() {
 var (
 	output = cmdExport.Flag.String("o", "", "output tar file name, must ends with .tar, or just a \"-\" for stdout")
 	format = cmdExport.Flag.String("fileNameFormat", defaultFnFormat, "filename formatted with {{.Mime}} {{.Id}} {{.Name}} {{.Ext}}")
-	newer  = cmdExport.Flag.String("newer", "", "export only files newer than this time, default is all files. Must be specified in RFC3339 without timezone")
+	newer  = cmdExport.Flag.String("newer", "", "export only files newer than this time, default is all files. Must be specified in RFC3339 without timezone, e.g. 2006-01-02T15:04:05")
 
 	tarOutputFile          *tar.Writer
 	tarHeader              tar.Header