diff --git a/swh/model/hypothesis_strategies.py b/swh/model/hypothesis_strategies.py
index a79bf10936abe90f75f5dd00620aa5c0e5911e55..18d46ba1a7f9989c870d3c7892c69f5427048002 100644
--- a/swh/model/hypothesis_strategies.py
+++ b/swh/model/hypothesis_strategies.py
@@ -191,7 +191,7 @@ def origin_visit_statuses():
 def releases_d(draw):
     target_type = sampled_from([x.value for x in ObjectType])
     name = binary()
-    message = binary()
+    message = optional(binary())
     synthetic = booleans()
     target = sha1_git()
     metadata = optional(revision_metadata())