diff --git a/src/allmydata/download.py b/src/allmydata/download.py
index 94ccf50ff..10c778954 100644
--- a/src/allmydata/download.py
+++ b/src/allmydata/download.py
@@ -223,7 +223,7 @@ class FileHandle:
         pass
 
 class IDownloader(Interface):
-    def download(verifierid, target):
+    def download(uri, target):
         pass
 
 class Downloader(service.MultiService):