diff --git a/zerver/lib/retention.py b/zerver/lib/retention.py
index a3304855e6..f673bf9837 100644
--- a/zerver/lib/retention.py
+++ b/zerver/lib/retention.py
@@ -420,6 +420,7 @@ def archive_stream_messages(
     recipients = [stream.recipient for stream in streams]
     message_count = 0
     for recipient in recipients:
+        assert recipient is not None
         message_count += archive_messages_by_recipient(
             recipient,
             retention_policy_dict[recipient.type_id],
diff --git a/zerver/tests/test_message_dict.py b/zerver/tests/test_message_dict.py
index 8989d88a25..66ec605190 100644
--- a/zerver/tests/test_message_dict.py
+++ b/zerver/tests/test_message_dict.py
@@ -450,6 +450,7 @@ class MessageHydrationTest(ZulipTestCase):
 
         cordelia_recipient = cordelia.recipient
         # Cause the display_recipient to get cached:
+        assert cordelia_recipient is not None
         get_display_recipient(cordelia_recipient)
 
         # Change cordelia's email:
diff --git a/zerver/tests/test_message_fetch.py b/zerver/tests/test_message_fetch.py
index ee65571612..3c1c3b9d1c 100644
--- a/zerver/tests/test_message_fetch.py
+++ b/zerver/tests/test_message_fetch.py
@@ -1378,6 +1378,9 @@ class GetOldMessagesTest(ZulipTestCase):
         query_ids: Dict[str, Union[int, str]] = {}
 
         scotland_stream = get_stream("Scotland", hamlet_user.realm)
+        assert scotland_stream.recipient_id is not None
+        assert hamlet_user.recipient_id is not None
+        assert othello_user.recipient_id is not None
         query_ids["scotland_recipient"] = scotland_stream.recipient_id
         query_ids["hamlet_id"] = hamlet_user.id
         query_ids["othello_id"] = othello_user.id
diff --git a/zerver/tests/test_muting_topics.py b/zerver/tests/test_muting_topics.py
index 1e360bd31c..2a407fa069 100644
--- a/zerver/tests/test_muting_topics.py
+++ b/zerver/tests/test_muting_topics.py
@@ -118,6 +118,7 @@ class MutedTopicsTests(ZulipTestCase):
         # trying to mute the topic.  To do this, we patch the
         # topic_is_muted function to always return False when trying
         # to mute a topic that is already muted.
+        assert stream.recipient is not None
         add_topic_mute(
             user_profile=user,
             stream_id=stream.id,
diff --git a/zerver/views/message_fetch.py b/zerver/views/message_fetch.py
index c09e8c60d3..3280e09b89 100644
--- a/zerver/views/message_fetch.py
+++ b/zerver/views/message_fetch.py
@@ -298,6 +298,7 @@ class NarrowBuilder:
             return query.where(maybe_negate(cond))
 
         recipient = stream.recipient
+        assert recipient is not None
         cond = column("recipient_id", Integer) == recipient.id
         return query.where(maybe_negate(cond))
 
diff --git a/zerver/views/message_flags.py b/zerver/views/message_flags.py
index 8670baca1e..ebb76b222b 100644
--- a/zerver/views/message_flags.py
+++ b/zerver/views/message_flags.py
@@ -82,6 +82,7 @@ def mark_topic_as_read(
     topic_name: str = REQ(),
 ) -> HttpResponse:
     stream, sub = access_stream_by_id(user_profile, stream_id)
+    assert stream.recipient_id is not None
 
     if topic_name:
         topic_exists = user_message_exists_for_topic(