diff --git a/mercurial/interfaces/repository.py b/mercurial/interfaces/repository.py
--- a/mercurial/interfaces/repository.py
+++ b/mercurial/interfaces/repository.py
@@ -15,6 +15,9 @@
 # we should move this to just "narrow" or similar.
 NARROW_REQUIREMENT = b'narrowhg-experimental'
 
+# Enables sparse working directory usage
+SPARSE_REQUIREMENT = b'exp-sparse'
+
 # 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
@@ -816,7 +816,7 @@
 
     ``error.RepoError`` should be raised on failure.
     """
-    if b'exp-sparse' in requirements and not sparse.enabled:
+    if repository.SPARSE_REQUIREMENT in requirements and not sparse.enabled:
         raise error.RepoError(
             _(
                 b'repository is using sparse feature but '
@@ -1067,7 +1067,7 @@
         b'shared',
         b'relshared',
         b'dotencode',
-        b'exp-sparse',
+        repository.SPARSE_REQUIREMENT,
         b'internal-phase',
     }
 
diff --git a/mercurial/sparse.py b/mercurial/sparse.py
--- a/mercurial/sparse.py
+++ b/mercurial/sparse.py
@@ -24,8 +24,10 @@
     scmutil,
     util,
 )
+from .interfaces import repository
 from .utils import hashutil
 
+
 # Whether sparse features are enabled. This variable is intended to be
 # temporary to facilitate porting sparse to core. It should eventually be
 # a per-repo option, possibly a repo requirement.
@@ -606,11 +608,11 @@
     # updated. But this requires massive rework to matcher() and its
     # consumers.
 
-    if b'exp-sparse' in oldrequires and removing:
-        repo.requirements.discard(b'exp-sparse')
+    if repository.SPARSE_REQUIREMENT in oldrequires and removing:
+        repo.requirements.discard(repository.SPARSE_REQUIREMENT)
         scmutil.writereporequirements(repo)
-    elif b'exp-sparse' not in oldrequires:
-        repo.requirements.add(b'exp-sparse')
+    elif repository.SPARSE_REQUIREMENT not in oldrequires:
+        repo.requirements.add(repository.SPARSE_REQUIREMENT)
         scmutil.writereporequirements(repo)
 
     try: