diff --git a/swh/model/hypothesis_strategies.py b/swh/model/hypothesis_strategies.py
--- a/swh/model/hypothesis_strategies.py
+++ b/swh/model/hypothesis_strategies.py
@@ -209,29 +209,16 @@
     metadata = optional(revision_metadata())
 
     return draw(
-        one_of(
-            builds(
-                dict,
-                name=name,
-                message=message,
-                synthetic=synthetic,
-                author=none(),
-                date=none(),
-                target=target,
-                target_type=target_type,
-                metadata=metadata,
-            ),
-            builds(
-                dict,
-                name=name,
-                message=message,
-                synthetic=synthetic,
-                date=timestamps_with_timezone_d(),
-                author=persons_d(),
-                target=target,
-                target_type=target_type,
-                metadata=metadata,
-            ),
+        builds(
+            dict,
+            name=name,
+            message=message,
+            synthetic=synthetic,
+            date=optional(timestamps_with_timezone_d()),
+            author=optional(persons_d()),
+            target=target,
+            target_type=target_type,
+            metadata=metadata,
         )
     )
 
diff --git a/swh/model/model.py b/swh/model/model.py
--- a/swh/model/model.py
+++ b/swh/model/model.py
@@ -628,12 +628,6 @@
         git_object = git_objects.release_git_object(self)
         return hashlib.new("sha1", git_object).digest()
 
-    @author.validator
-    def check_author(self, attribute, value):
-        """If the author is `None`, checks the date is `None` too."""
-        if self.author is None and self.date is not None:
-            raise ValueError("release date must be None if author is None.")
-
     def to_dict(self):
         rel = super().to_dict()
         if rel["metadata"] is None: