diff --git a/hgext/clonebundles.py b/hgext/clonebundles.py
--- a/hgext/clonebundles.py
+++ b/hgext/clonebundles.py
@@ -205,6 +205,7 @@
 from __future__ import absolute_import
 
 from mercurial import (
+    bundlecaches,
     extensions,
     wireprotov1server,
 )
@@ -218,7 +219,7 @@
     # Only advertise if a manifest exists. This does add some I/O to requests.
     # But this should be cheaper than a wasted network round trip due to
     # missing file.
-    if repo.vfs.exists(b'clonebundles.manifest'):
+    if repo.vfs.exists(bundlecaches.CB_MANIFEST_FILE):
         caps.append(b'clonebundles')
 
     return caps
diff --git a/mercurial/bundlecaches.py b/mercurial/bundlecaches.py
--- a/mercurial/bundlecaches.py
+++ b/mercurial/bundlecaches.py
@@ -16,6 +16,8 @@
 
 urlreq = util.urlreq
 
+CB_MANIFEST_FILE = b'clonebundles.manifest'
+
 
 @attr.s
 class bundlespec(object):
diff --git a/mercurial/localrepo.py b/mercurial/localrepo.py
--- a/mercurial/localrepo.py
+++ b/mercurial/localrepo.py
@@ -31,6 +31,7 @@
     bookmarks,
     branchmap,
     bundle2,
+    bundlecaches,
     changegroup,
     color,
     commit,
@@ -299,7 +300,7 @@
         return self._caps
 
     def clonebundles(self):
-        return self._repo.tryread(b'clonebundles.manifest')
+        return self._repo.tryread(bundlecaches.CB_MANIFEST_FILE)
 
     def debugwireargs(self, one, two, three=None, four=None, five=None):
         """Used to test argument passing over the wire"""
diff --git a/mercurial/wireprotov1server.py b/mercurial/wireprotov1server.py
--- a/mercurial/wireprotov1server.py
+++ b/mercurial/wireprotov1server.py
@@ -273,7 +273,7 @@
     data center given the client's IP address.
     """
     return wireprototypes.bytesresponse(
-        repo.vfs.tryread(b'clonebundles.manifest')
+        repo.vfs.tryread(bundlecaches.CB_MANIFEST_FILE)
     )