diff --git a/mercurial/revlogutils/nodemap.py b/mercurial/revlogutils/nodemap.py
--- a/mercurial/revlogutils/nodemap.py
+++ b/mercurial/revlogutils/nodemap.py
@@ -268,7 +268,7 @@
 # nodemap gains the necessary features to be used in production.
 
 # version 0 is experimental, no BC garantee, do no use outside of tests.
-ONDISK_VERSION = 0
+ONDISK_VERSION = 1
 S_VERSION = struct.Struct(">B")
 S_HEADER = struct.Struct(">BQQQQ")