diff --git a/warcprox/bigtable.py b/warcprox/bigtable.py
index 387d05c..f3d897d 100644
--- a/warcprox/bigtable.py
+++ b/warcprox/bigtable.py
@@ -220,7 +220,7 @@ class RethinkCapturesDedup:
         self.captures_db = captures_db
         self.options = options
 
-    def lookup(self, digest_key, bucket="__unspecified__"):
+    def lookup(self, digest_key, bucket="__unspecified__", url=None):
         k = digest_key.decode("utf-8") if isinstance(digest_key, bytes) else digest_key
         algo, value_str = k.split(":")
         if self.options.base32: