diff --git a/README.md b/README.md
index d72407c..f4a0207 100644
--- a/README.md
+++ b/README.md
@@ -158,6 +158,7 @@ Publication checklist. Do these from _outside_ the webdiff directory:
 
 - Run `webdiff webdiff/testdata/.../{left,right}`
 - Run `git webdiff 52aa15f^..52aa15f` in the codediff.js repo
+- Run `git webshow 52aa15f` from the codediff.js repo (should be same as previous command)
 - Run `webdiff https://github.com/danvk/webdiff/pull/160`
 
 ## Implementation notes
diff --git a/webdiff/gitwebdiff.py b/webdiff/gitwebdiff.py
index 114dbf6..7e07633 100755
--- a/webdiff/gitwebdiff.py
+++ b/webdiff/gitwebdiff.py
@@ -11,7 +11,7 @@ def any_nonflag_args(args):
     return len([x for x in args if not x.startswith('-')]) > 0
 
 
-def run(argv):
+def run(argv=sys.argv):
     if os.environ.get('DEBUG'):
         sys.stderr.write(f'git webdiff invoked as: {argv}\n')