diff --git a/src/__init__.py b/src/__init__.py
--- a/src/__init__.py
+++ b/src/__init__.py
@@ -17,6 +17,7 @@
     extensions,
     hg,
     localrepo,
+    registrar,
     util,
     verify as verifymod,
 )
@@ -35,6 +36,12 @@
     narrowwirepeer,
 )
 
+configtable = {}
+configitem = registrar.configitem(configtable)
+configitem('narrow', 'serveellipses',
+           default=False,
+)
+
 # Export the commands table for Mercurial to see.
 cmdtable = narrowcommands.table
 
diff --git a/src/narrowbundle2.py b/src/narrowbundle2.py
--- a/src/narrowbundle2.py
+++ b/src/narrowbundle2.py
@@ -222,7 +222,7 @@
     include = sorted(filter(bool, kwargs.get('includepats', [])))
     exclude = sorted(filter(bool, kwargs.get('excludepats', [])))
     newmatch = narrowspec.match(repo.root, include=include, exclude=exclude)
-    if not repo.ui.configbool("narrow", "serveellipses", False):
+    if not repo.ui.configbool("narrow", "serveellipses"):
         outgoing = exchange._computeoutgoing(repo, heads, common)
         if not outgoing.missing:
             return
@@ -430,4 +430,3 @@
             handlechangegroup_widen(op, inpart)
     wrappedcghandler.params = origcghandler.params
     bundle2.parthandlermapping['changegroup'] = wrappedcghandler
-