--- a/mercurial/commands.py	Mon Feb 06 23:02:48 2017 -0500
+++ b/mercurial/commands.py	Mon Feb 06 23:09:15 2017 -0500
@@ -2606,6 +2606,7 @@
                 except error.LookupError:
                     pass
 
+    ui.pager('grep')
     fm = ui.formatter('grep', opts)
     for ctx in cmdutil.walkchangerevs(repo, matchfn, opts, prep):
         rev = ctx.rev()