1 files changed, 6 insertions, 2 deletions
diff --git a/synapse/storage/util/sequence.py b/synapse/storage/util/sequence.py
index 0ec4dc2918..e2b316a218 100644
--- a/synapse/storage/util/sequence.py
+++ b/synapse/storage/util/sequence.py
@@ -106,7 +106,9 @@ class PostgresSequenceGenerator(SequenceGenerator):
 
     def get_next_id_txn(self, txn: Cursor) -> int:
         txn.execute("SELECT nextval(?)", (self._sequence_name,))
-        return txn.fetchone()[0]
+        fetch_res = txn.fetchone()
+        assert fetch_res is not None
+        return fetch_res[0]
 
     def get_next_mult_txn(self, txn: Cursor, n: int) -> List[int]:
         txn.execute(
@@ -147,7 +149,9 @@ class PostgresSequenceGenerator(SequenceGenerator):
         txn.execute(
             "SELECT last_value, is_called FROM %(seq)s" % {"seq": self._sequence_name}
         )
-        last_value, is_called = txn.fetchone()
+        fetch_res = txn.fetchone()
+        assert fetch_res is not None
+        last_value, is_called = fetch_res
 
         # If we have an associated stream check the stream_positions table.
         max_in_stream_positions = None