diff --git a/mercurial/hgweb/protocol.py b/mercurial/hgweb/protocol.py
--- a/mercurial/hgweb/protocol.py
+++ b/mercurial/hgweb/protocol.py
@@ -73,13 +73,13 @@ class webproto(wireproto.abstractserverp
         val = self.ui.fout.getvalue()
         self.ui.ferr, self.ui.fout = self.oldio
         return val
-    def groupchunks(self, cg):
+    def groupchunks(self, fh):
         # Don't allow untrusted settings because disabling compression or
         # setting a very high compression level could lead to flooding
         # the server's network or CPU.
         z = zlib.compressobj(self.ui.configint('server', 'zliblevel', -1))
         while True:
-            chunk = cg.read(32768)
+            chunk = fh.read(32768)
             if not chunk:
                 break
             data = z.compress(chunk)
diff --git a/mercurial/sshserver.py b/mercurial/sshserver.py
--- a/mercurial/sshserver.py
+++ b/mercurial/sshserver.py
@@ -68,8 +68,8 @@ class sshserver(wireproto.abstractserver
     def redirect(self):
         pass
 
-    def groupchunks(self, changegroup):
-        return iter(lambda: changegroup.read(4096), '')
+    def groupchunks(self, fh):
+        return iter(lambda: fh.read(4096), '')
 
     def sendresponse(self, v):
         self.fout.write("%d\n" % len(v))
diff --git a/mercurial/wireproto.py b/mercurial/wireproto.py
--- a/mercurial/wireproto.py
+++ b/mercurial/wireproto.py
@@ -78,10 +78,11 @@ class abstractserverproto(object):
     #    """
     #    raise NotImplementedError()
 
-    def groupchunks(self, cg):
-        """return 4096 chunks from a changegroup object
+    def groupchunks(self, fh):
+        """Generator of chunks to send to the client.
 
-        Some protocols may have compressed the contents."""
+        Some protocols may have compressed the contents.
+        """
         raise NotImplementedError()
 
 class remotebatch(peer.batcher):