diff --git a/contrib/perf.py b/contrib/perf.py
--- a/contrib/perf.py
+++ b/contrib/perf.py
@@ -150,6 +150,9 @@ try:
     configitem('perf', 'stub',
         default=mercurial.configitems.dynamicdefault,
     )
+    configitem('perf', 'parentscount',
+        default=mercurial.configitems.dynamicdefault,
+    )
 except (ImportError, AttributeError):
     pass