diff --git a/swh/objstorage/backends/winery/objstorage.py b/swh/objstorage/backends/winery/objstorage.py
--- a/swh/objstorage/backends/winery/objstorage.py
+++ b/swh/objstorage/backends/winery/objstorage.py
@@ -141,14 +141,14 @@
         self.shard.uninit()
         super().uninit()
 
-    def add(self, content: bytes, obj_id: ObjId, check_presence: bool = True) -> ObjId:
+    def add(self, content: bytes, obj_id: ObjId, check_presence: bool = True) -> None:
         if check_presence and obj_id in self:
-            return obj_id
+            return
 
         shard = self.base.add_phase_1(obj_id)
         if shard != self.base.id:
             #  this object is the responsibility of another shard
-            return obj_id
+            return
 
         self.shard.add(obj_id, content)
         self.base.add_phase_2(obj_id)
@@ -156,8 +156,6 @@
         if self.shard.is_full():
             self.pack()
 
-        return obj_id
-
     def check(self, obj_id: ObjId) -> None:
         # load all shards packing == True and not locked (i.e. packer
         # was interrupted for whatever reason) run pack for each of them
diff --git a/swh/objstorage/tests/test_objstorage_winery.py b/swh/objstorage/tests/test_objstorage_winery.py
--- a/swh/objstorage/tests/test_objstorage_winery.py
+++ b/swh/objstorage/tests/test_objstorage_winery.py
@@ -97,13 +97,14 @@
 def test_winery_add_get(winery):
     shard = winery.base.whoami
     content = b"SOMETHING"
-    obj_id = winery.add(content=content, obj_id=compute_hash(content, "sha256"))
+    obj_id = compute_hash(content, "sha256")
     assert (
         obj_id.hex()
         == "866878b165607851782d8d233edf0c261172ff67926330d3bbd10c705b92d24f"
     )
-    assert winery.add(content=content, obj_id=obj_id) == obj_id
-    assert winery.add(content=content, obj_id=obj_id, check_presence=False) == obj_id
+    winery.add(content=content, obj_id=obj_id)
+    winery.add(content=content, obj_id=obj_id)
+    winery.add(content=content, obj_id=obj_id, check_presence=False)
     assert winery.base.whoami == shard
     assert winery.get(obj_id) == content
     with pytest.raises(exc.ObjNotFoundError):
@@ -116,11 +117,7 @@
     mocker.patch("swh.objstorage.backends.winery.objstorage.pack", return_value=True)
     shard = winery.base.whoami
     content = b"SOMETHING"
-    obj_id = winery.add(content=content, obj_id=compute_hash(content, "sha256"))
-    assert (
-        obj_id.hex()
-        == "866878b165607851782d8d233edf0c261172ff67926330d3bbd10c705b92d24f"
-    )
+    winery.add(content=content, obj_id=compute_hash(content, "sha256"))
     assert winery.base.whoami != shard
     assert len(winery.packers) == 1
     packer = winery.packers[0]