diff --git a/mercurial/wireproto.py b/mercurial/wireproto.py
--- a/mercurial/wireproto.py
+++ b/mercurial/wireproto.py
@@ -324,6 +324,8 @@ class wirepeer(peer.peerrepository):
         self.ui.debug('preparing listkeys for "%s"\n' % namespace)
         yield {'namespace': encoding.fromlocal(namespace)}, f
         d = f.value
+        self.ui.debug('received listkey for "%s": %i bytes\n'
+                      % (namespace, len(d)))
         yield pushkeymod.decodekeys(d)
 
     def stream_out(self):
diff --git a/tests/test-ssh.t b/tests/test-ssh.t
--- a/tests/test-ssh.t
+++ b/tests/test-ssh.t
@@ -457,8 +457,10 @@ debug output
   remote: 1
   preparing listkeys for "bookmarks"
   sending listkeys command
+  received listkey for "bookmarks": 45 bytes
   preparing listkeys for "bookmarks"
   sending listkeys command
+  received listkey for "bookmarks": 45 bytes
   query 1; heads
   sending batch command
   searching for changes
@@ -466,6 +468,7 @@ debug output
   no changes found
   preparing listkeys for "phases"
   sending listkeys command
+  received listkey for "phases": 15 bytes
   checking for updated bookmarks
 
   $ cd ..