diff --git a/mercurial/localrepo.py b/mercurial/localrepo.py
--- a/mercurial/localrepo.py
+++ b/mercurial/localrepo.py
@@ -3639,11 +3639,11 @@
         # effectively locks out old clients and prevents them from
         # mucking with a repo in an unknown format.
         #
-        # The revlog header has version 2, which won't be recognized by
+        # The revlog header has version 65535, which won't be recognized by
         # such old clients.
         hgvfs.append(
             b'00changelog.i',
-            b'\0\0\0\2 dummy changelog to prevent using the old repo '
+            b'\0\0\xFF\xFF dummy changelog to prevent using the old repo '
             b'layout',
         )
 
diff --git a/tests/test-requires.t b/tests/test-requires.t
--- a/tests/test-requires.t
+++ b/tests/test-requires.t
@@ -5,7 +5,7 @@
   $ hg commit -m test
   $ rm .hg/requires
   $ hg tip
-  abort: unknown version (2) in revlog 00changelog.i
+  abort: unknown version (65535) in revlog 00changelog.i
   [50]
   $ echo indoor-pool > .hg/requires
   $ hg tip