diff --git a/hgext/narrow/narrowbundle2.py b/hgext/narrow/narrowbundle2.py
--- a/hgext/narrow/narrowbundle2.py
+++ b/hgext/narrow/narrowbundle2.py
@@ -108,7 +108,7 @@ def generateellipsesbundle2(
 
         part = bundler.newpart(b'changegroup', data=cgdata)
         part.addparam(b'version', version)
-        if b'treemanifest' in repo.requirements:
+        if repository.TREEMANIFEST_REQUIREMENT in repo.requirements:
             part.addparam(b'treemanifest', b'1')
 
 
@@ -163,7 +163,7 @@ def generate_ellipses_bundle2_for_wideni
 
         part = bundler.newpart(b'changegroup', data=cgdata)
         part.addparam(b'version', version)
-        if b'treemanifest' in repo.requirements:
+        if repository.TREEMANIFEST_REQUIREMENT in repo.requirements:
             part.addparam(b'treemanifest', b'1')
 
 
diff --git a/hgext/remotefilelog/remotefilelogserver.py b/hgext/remotefilelog/remotefilelogserver.py
--- a/hgext/remotefilelog/remotefilelogserver.py
+++ b/hgext/remotefilelog/remotefilelogserver.py
@@ -30,6 +30,7 @@ from mercurial import (
     wireprototypes,
     wireprotov1server,
 )
+from mercurial.interfaces import repository
 from . import (
     constants,
     shallowutil,
@@ -169,7 +170,7 @@ def onetimesetup(ui):
                         if kind == stat.S_IFDIR:
                             visit.append(fp)
 
-            if b'treemanifest' in repo.requirements:
+            if repository.TREEMANIFEST_REQUIREMENT in repo.requirements:
                 for (u, e, s) in repo.store.datafiles():
                     if u.startswith(b'meta/') and (
                         u.endswith(b'.i') or u.endswith(b'.d')
diff --git a/mercurial/bundle2.py b/mercurial/bundle2.py
--- a/mercurial/bundle2.py
+++ b/mercurial/bundle2.py
@@ -172,6 +172,7 @@ from . import (
     url,
     util,
 )
+from .interfaces import repository
 from .utils import stringutil
 
 urlerr = util.urlerr
@@ -1965,7 +1966,7 @@ def handlechangegroup(op, inpart):
         nbchangesets = int(inpart.params.get(b'nbchanges'))
     if (
         b'treemanifest' in inpart.params
-        and b'treemanifest' not in op.repo.requirements
+        and repository.TREEMANIFEST_REQUIREMENT not in op.repo.requirements
     ):
         if len(op.repo.changelog) != 0:
             raise error.Abort(
@@ -1974,7 +1975,7 @@ def handlechangegroup(op, inpart):
                     b"non-empty and does not use tree manifests"
                 )
             )
-        op.repo.requirements.add(b'treemanifest')
+        op.repo.requirements.add(repository.TREEMANIFEST_REQUIREMENT)
         op.repo.svfs.options = localrepo.resolvestorevfsoptions(
             op.repo.ui, op.repo.requirements, op.repo.features
         )
@@ -2576,7 +2577,7 @@ def widen_bundle(
 
         part = bundler.newpart(b'changegroup', data=cgdata)
         part.addparam(b'version', cgversion)
-        if b'treemanifest' in repo.requirements:
+        if repository.TREEMANIFEST_REQUIREMENT in repo.requirements:
             part.addparam(b'treemanifest', b'1')
         if b'exp-sidedata-flag' in repo.requirements:
             part.addparam(b'exp-sidedata', b'1')
diff --git a/mercurial/changegroup.py b/mercurial/changegroup.py
--- a/mercurial/changegroup.py
+++ b/mercurial/changegroup.py
@@ -949,7 +949,7 @@ class cgpacker(object):
         # either, because we don't discover which directory nodes to
         # send along with files. This could probably be fixed.
         fastpathlinkrev = fastpathlinkrev and (
-            b'treemanifest' not in repo.requirements
+            repository.TREEMANIFEST_REQUIREMENT not in repo.requirements
         )
 
         fnodes = {}  # needed file nodes
@@ -1467,7 +1467,7 @@ def allsupportedversions(repo):
     if (
         repo.ui.configbool(b'experimental', b'changegroup3')
         or repo.ui.configbool(b'experimental', b'treemanifest')
-        or b'treemanifest' in repo.requirements
+        or repository.TREEMANIFEST_REQUIREMENT in repo.requirements
     ):
         # we keep version 03 because we need to to exchange treemanifest data
         #
@@ -1495,7 +1495,7 @@ def supportedincomingversions(repo):
 # Changegroup versions that can be created from the repo
 def supportedoutgoingversions(repo):
     versions = allsupportedversions(repo)
-    if b'treemanifest' in repo.requirements:
+    if repository.TREEMANIFEST_REQUIREMENT in repo.requirements:
         # Versions 01 and 02 support only flat manifests and it's just too
         # expensive to convert between the flat manifest and tree manifest on
         # the fly. Since tree manifests are hashed differently, all of history
diff --git a/mercurial/cmdutil.py b/mercurial/cmdutil.py
--- a/mercurial/cmdutil.py
+++ b/mercurial/cmdutil.py
@@ -58,6 +58,8 @@ from . import (
     vfs as vfsmod,
 )
 
+from .interfaces import repository
+
 from .utils import (
     dateutil,
     stringutil,
@@ -1358,7 +1360,7 @@ def openstorage(repo, cmd, file_, opts, 
         if cl:
             r = repo.unfiltered().changelog
         elif dir:
-            if b'treemanifest' not in repo.requirements:
+            if repository.TREEMANIFEST_REQUIREMENT not in repo.requirements:
                 raise error.Abort(
                     _(
                         b"--dir can only be used on repos with "
diff --git a/mercurial/exchange.py b/mercurial/exchange.py
--- a/mercurial/exchange.py
+++ b/mercurial/exchange.py
@@ -1068,7 +1068,7 @@ def _pushb2ctx(pushop, bundler):
     cgpart = bundler.newpart(b'changegroup', data=cgstream)
     if cgversions:
         cgpart.addparam(b'version', version)
-    if b'treemanifest' in pushop.repo.requirements:
+    if repository.TREEMANIFEST_REQUIREMENT in pushop.repo.requirements:
         cgpart.addparam(b'treemanifest', b'1')
     if b'exp-sidedata-flag' in pushop.repo.requirements:
         cgpart.addparam(b'exp-sidedata', b'1')
@@ -2557,7 +2557,7 @@ def _getbundlechangegrouppart(
 
     part.addparam(b'nbchanges', b'%d' % len(outgoing.missing), mandatory=False)
 
-    if b'treemanifest' in repo.requirements:
+    if repository.TREEMANIFEST_REQUIREMENT in repo.requirements:
         part.addparam(b'treemanifest', b'1')
 
     if b'exp-sidedata-flag' in repo.requirements:
diff --git a/mercurial/interfaces/repository.py b/mercurial/interfaces/repository.py
--- a/mercurial/interfaces/repository.py
+++ b/mercurial/interfaces/repository.py
@@ -22,6 +22,9 @@ SPARSE_REQUIREMENT = b'exp-sparse'
 # of stripping them
 INTERNAL_PHASE_REQUIREMENT = b'internal-phase'
 
+# Stores manifest in Tree structure
+TREEMANIFEST_REQUIREMENT = b'treemanifest'
+
 # Local repository feature string.
 
 # Revlogs are being used for file storage.
diff --git a/mercurial/localrepo.py b/mercurial/localrepo.py
--- a/mercurial/localrepo.py
+++ b/mercurial/localrepo.py
@@ -846,7 +846,7 @@ def resolvestorevfsoptions(ui, requireme
     """
     options = {}
 
-    if b'treemanifest' in requirements:
+    if repository.TREEMANIFEST_REQUIREMENT in requirements:
         options[b'treemanifest'] = True
 
     # experimental config: format.manifestcachesize
@@ -1053,7 +1053,7 @@ class localrepository(object):
     supportedformats = {
         b'revlogv1',
         b'generaldelta',
-        b'treemanifest',
+        repository.TREEMANIFEST_REQUIREMENT,
         COPIESSDC_REQUIREMENT,
         REVLOGV2_REQUIREMENT,
         SIDEDATA_REQUIREMENT,
@@ -3314,7 +3314,7 @@ def newreporequirements(ui, createopts):
         requirements.add(SIDEDATA_REQUIREMENT)
         requirements.add(COPIESSDC_REQUIREMENT)
     if ui.configbool(b'experimental', b'treemanifest'):
-        requirements.add(b'treemanifest')
+        requirements.add(repository.TREEMANIFEST_REQUIREMENT)
 
     revlogv2 = ui.config(b'experimental', b'revlogv2')
     if revlogv2 == b'enable-unstable-format-and-corrupt-my-data':
diff --git a/mercurial/repair.py b/mercurial/repair.py
--- a/mercurial/repair.py
+++ b/mercurial/repair.py
@@ -28,6 +28,7 @@ from . import (
     pycompat,
     util,
 )
+from .interfaces import repository
 from .utils import (
     hashutil,
     stringutil,
@@ -418,7 +419,7 @@ def stripmanifest(repo, striprev, tr, fi
 
 def manifestrevlogs(repo):
     yield repo.manifestlog.getstorage(b'')
-    if b'treemanifest' in repo.requirements:
+    if repository.TREEMANIFEST_REQUIREMENT in repo.requirements:
         # This logic is safe if treemanifest isn't enabled, but also
         # pointless, so we skip it if treemanifest isn't enabled.
         for unencoded, encoded, size in repo.store.datafiles():
@@ -476,7 +477,7 @@ def rebuildfncache(ui, repo):
 
         progress.complete()
 
-        if b'treemanifest' in repo.requirements:
+        if repository.TREEMANIFEST_REQUIREMENT in repo.requirements:
             # This logic is safe if treemanifest isn't enabled, but also
             # pointless, so we skip it if treemanifest isn't enabled.
             for dir in pathutil.dirs(seenfiles):
diff --git a/mercurial/upgrade.py b/mercurial/upgrade.py
--- a/mercurial/upgrade.py
+++ b/mercurial/upgrade.py
@@ -26,6 +26,7 @@ from . import (
     vfs as vfsmod,
 )
 
+from .interfaces import repository
 from .utils import compression
 
 # list of requirements that request a clone of all revlog if added/removed
@@ -58,7 +59,7 @@ def blocksourcerequirements(repo):
     return {
         # The upgrade code does not yet support these experimental features.
         # This is an artificial limitation.
-        b'treemanifest',
+        repository.TREEMANIFEST_REQUIREMENT,
         # This was a precursor to generaldelta and was never enabled by default.
         # It should (hopefully) not exist in the wild.
         b'parentdelta',