diff --git a/remotefilelog/remotefilelogserver.py b/remotefilelog/remotefilelogserver.py
--- a/remotefilelog/remotefilelogserver.py
+++ b/remotefilelog/remotefilelogserver.py
@@ -7,7 +7,8 @@
 from __future__ import absolute_import
 
 from mercurial import wireproto, changegroup, match, util, changelog, context
-from mercurial import exchange, store, error
+from mercurial import store, error
+from mercurial import streamclone
 from mercurial.extensions import wrapfunction
 from mercurial.node import bin, hex, nullid, nullrev
 from mercurial.i18n import _
@@ -28,13 +29,6 @@
     _sshv1server = wireprotoserver.sshv1protocolhandler
 
 try:
-    from mercurial import streamclone
-    streamclone._walkstreamfiles
-    hasstreamclone = True
-except Exception:
-    hasstreamclone = False
-
-try:
     # hg 4.6 and later
     from mercurial import wireprotoserver as httpprotocol
     httpprotocol.HTTP_OK # force demandimport
@@ -183,13 +177,7 @@
             for x in orig(repo):
                 yield x
 
-    # This function moved in Mercurial 3.5 and 3.6
-    if hasstreamclone:
-        wrapfunction(streamclone, '_walkstreamfiles', _walkstreamfiles)
-    elif util.safehasattr(wireproto, '_walkstreamfiles'):
-        wrapfunction(wireproto, '_walkstreamfiles', _walkstreamfiles)
-    else:
-        wrapfunction(exchange, '_walkstreamfiles', _walkstreamfiles)
+    wrapfunction(streamclone, '_walkstreamfiles', _walkstreamfiles)
 
     # We no longer use getbundle_shallow commands, but we must still
     # support it for migration purposes