diff --git a/swh/model/model.py b/swh/model/model.py
index 1c54004f3b03f2ed0dd34b9076e6e935ae9a04d4..5f2d960a8a7bf6be2dc943c27ebd5deb6c74a287 100644
--- a/swh/model/model.py
+++ b/swh/model/model.py
@@ -12,6 +12,8 @@ import dateutil.parser
 
 from .identifiers import normalize_timestamp
 
+SHA1_SIZE = 20
+
 # TODO: Limit this to 20 bytes
 Sha1Git = bytes