1 files changed, 7 insertions, 4 deletions
diff --git a/synapse/storage/util/sequence.py b/synapse/storage/util/sequence.py
index 0ec4dc2918..3ea637b281 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(
@@ -122,8 +124,7 @@ class PostgresSequenceGenerator(SequenceGenerator):
         stream_name: Optional[str] = None,
         positive: bool = True,
     ):
-        """See SequenceGenerator.check_consistency for docstring.
-        """
+        """See SequenceGenerator.check_consistency for docstring."""
 
         txn = db_conn.cursor(txn_name="sequence.check_consistency")
 
@@ -147,7 +148,9 @@ 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