diff --git a/contrib/check-config.py b/contrib/check-config.py
--- a/contrib/check-config.py
+++ b/contrib/check-config.py
@@ -105,4 +105,7 @@ def main(args):
                 print "undocumented: %s (%s)%s" % (name, ctype, default)
 
 if __name__ == "__main__":
-    sys.exit(main(sys.argv[1:]))
+    if len(sys.argv) > 1:
+        sys.exit(main(sys.argv[1:]))
+    else:
+        sys.exit(main([l.rstrip() for l in sys.stdin]))
diff --git a/tests/test-check-config.t b/tests/test-check-config.t
--- a/tests/test-check-config.t
+++ b/tests/test-check-config.t
@@ -5,4 +5,4 @@
 New errors are not allowed. Warnings are strongly discouraged.
 
   $ hg files "set:(**.py or **.txt) - tests/**" | sed 's|\\|/|g' |
-  >   xargs python contrib/check-config.py
+  >   python contrib/check-config.py