diff --git a/swh/storage/postgresql/db.py b/swh/storage/postgresql/db.py
--- a/swh/storage/postgresql/db.py
+++ b/swh/storage/postgresql/db.py
@@ -779,19 +779,21 @@
         """
         cur = self._cursor(cur)
 
+        # using 'LEFT JOIN origin_visit' instead of an INNER JOIN as a query
+        # optimization; end results are equivalent.
         query_parts = [
             "SELECT %s" % ", ".join(self.origin_visit_select_cols),
-            "FROM origin_visit ov ",
-            "INNER JOIN origin o ON o.id = ov.origin",
-            "INNER JOIN origin_visit_status ovs USING (origin, visit)",
+            "FROM origin_visit_status ovs ",
+            "INNER JOIN origin o ON o.id = ovs.origin",
+            "LEFT JOIN origin_visit ov USING (origin, visit)",
         ]
         query_parts.append(
-            "WHERE ov.origin = (SELECT id FROM origin o WHERE o.url = %s)"
+            "WHERE ovs.origin = (SELECT id FROM origin o WHERE o.url = %s)"
         )
         query_params: List[Any] = [origin_id]
 
         if type is not None:
-            query_parts.append("AND ov.type = %s")
+            query_parts.append("AND ovs.type = %s")
             query_params.append(type)
 
         if require_snapshot:
@@ -801,7 +803,7 @@
             query_parts.append("AND ovs.status IN %s")
             query_params.append(tuple(allowed_statuses))
 
-        query_parts.append("ORDER BY ov.visit DESC, ovs.date DESC LIMIT 1")
+        query_parts.append("ORDER BY ovs.visit DESC, ovs.date DESC LIMIT 1")
 
         query = "\n".join(query_parts)
 
diff --git a/swh/storage/postgresql/storage.py b/swh/storage/postgresql/storage.py
--- a/swh/storage/postgresql/storage.py
+++ b/swh/storage/postgresql/storage.py
@@ -1290,6 +1290,9 @@
         )
         if row:
             row_d = dict(zip(db.origin_visit_get_cols, row))
+            assert (
+                row_d["visit"] is not None
+            ), "origin_visit_status LEFT JOIN origin_visit returned NULL"
             visit = OriginVisit(
                 origin=row_d["origin"],
                 visit=row_d["visit"],