diff --git a/swh/storage/validate.py b/swh/storage/validate.py
--- a/swh/storage/validate.py
+++ b/swh/storage/validate.py
@@ -106,10 +106,18 @@
             releases = [Release.from_dict(r) for r in releases]
         return self.storage.release_add(releases)
 
-    def snapshot_add(self, snapshots: Iterable[Dict]) -> Dict:
-        with convert_validation_exceptions():
-            snapshots = [Snapshot.from_dict(s) for s in snapshots]
-        return self.storage.snapshot_add(snapshots)
+    def snapshot_add(
+        self, snapshots: Union[Iterable[Dict], Iterable[Snapshot]]
+    ) -> Dict:
+        snapshots_: List[Snapshot] = []
+        for s in snapshots:
+            if isinstance(s, Dict):
+                with convert_validation_exceptions():
+                    snapshot = Snapshot.from_dict(s)
+            else:
+                snapshot = s
+            snapshots_.append(snapshot)
+        return self.storage.snapshot_add(snapshots_)
 
     def origin_visit_add(self, visits: Iterable[OriginVisit]) -> Iterable[OriginVisit]:
         return self.storage.origin_visit_add(visits)