diff --git a/subcmds/manifest.py b/subcmds/manifest.py
index 07fa323..768f072 100644
--- a/subcmds/manifest.py
+++ b/subcmds/manifest.py
@@ -73,14 +73,9 @@
     if opt.output_file != '-':
       print('Saved manifest to %s' % opt.output_file, file=sys.stderr)
 
-  def Execute(self, opt, args):
+  def ValidateOptions(self, opt, args):
     if args:
       self.Usage()
 
-    if opt.output_file is not None:
-      self._Output(opt)
-      return
-
-    print('error: no operation to perform', file=sys.stderr)
-    print('error: see repo help manifest', file=sys.stderr)
-    sys.exit(1)
+  def Execute(self, opt, args):
+    self._Output(opt)