diff --git a/zerver/lib/topic_mutes.py b/zerver/lib/topic_mutes.py
index f1a30df323..7898c5cdb6 100644
--- a/zerver/lib/topic_mutes.py
+++ b/zerver/lib/topic_mutes.py
@@ -1,5 +1,5 @@
 import datetime
-from typing import Any, Callable, Dict, List, Optional, Union
+from typing import Any, Callable, Dict, List, Optional, Tuple
 
 from django.utils.timezone import now as timezone_now
 from sqlalchemy.sql import Selectable, and_, column, not_, or_
@@ -9,7 +9,7 @@ from zerver.lib.topic import topic_match_sa
 from zerver.models import MutedTopic, UserProfile, get_stream
 
 
-def get_topic_mutes(user_profile: UserProfile) -> List[List[Union[str, float]]]:
+def get_topic_mutes(user_profile: UserProfile) -> List[Tuple[str, str, float]]:
     rows = MutedTopic.objects.filter(
         user_profile=user_profile,
     ).values(
@@ -18,7 +18,7 @@ def get_topic_mutes(user_profile: UserProfile) -> List[List[Union[str, float]]]:
         'date_muted',
     )
     return [
-        [row['stream__name'], row['topic_name'], datetime_to_timestamp(row['date_muted'])]
+        (row['stream__name'], row['topic_name'], datetime_to_timestamp(row['date_muted']))
         for row in rows
     ]
 
diff --git a/zerver/lib/validator.py b/zerver/lib/validator.py
index 5595f967dc..f887e69404 100644
--- a/zerver/lib/validator.py
+++ b/zerver/lib/validator.py
@@ -163,6 +163,24 @@ def check_list(sub_validator: Optional[Validator[ResultT]]=None, length: Optiona
         return cast(List[ResultT], val)
     return f
 
+def check_tuple(sub_validators: List[Validator[ResultT]]) -> Validator[Tuple[Any, ...]]:
+    def f(var_name: str, val: object) -> Tuple[Any, ...]:
+        if not isinstance(val, tuple):
+            raise ValidationError(_('{var_name} is not a tuple').format(var_name=var_name))
+
+        desired_len = len(sub_validators)
+        if desired_len != len(val):
+            raise ValidationError(_('{var_name} should have exactly {desired_len} items').format(
+                var_name=var_name, desired_len=desired_len,
+            ))
+
+        for i, sub_validator in enumerate(sub_validators):
+            vname = f'{var_name}[{i}]'
+            sub_validator(vname, val[i])
+
+        return val
+    return f
+
 # https://zulip.readthedocs.io/en/latest/testing/mypy.html#using-overload-to-accurately-describe-variations
 @overload
 def check_dict(required_keys: Iterable[Tuple[str, Validator[object]]]=[],
diff --git a/zerver/tests/test_decorators.py b/zerver/tests/test_decorators.py
index adda952e16..0302459ac3 100644
--- a/zerver/tests/test_decorators.py
+++ b/zerver/tests/test_decorators.py
@@ -68,6 +68,7 @@ from zerver.lib.validator import (
     check_string_in,
     check_string_or_int,
     check_string_or_int_list,
+    check_tuple,
     check_union,
     check_url,
     equals,
@@ -848,6 +849,21 @@ class ValidatorTestCase(TestCase):
         with self.assertRaisesRegex(ValidationError, r'color is not a string'):
             check_color('color', z)
 
+    def test_check_tuple(self) -> None:
+        x: Any = 999
+        with self.assertRaisesRegex(ValidationError, r'x is not a tuple'):
+            check_tuple([check_string])('x', x)
+
+        x = (5, 2)
+        with self.assertRaisesRegex(ValidationError, r'x\[0\] is not a string'):
+            check_tuple([check_string, check_string])('x', x)
+
+        x = (1, 2, 3)
+        with self.assertRaisesRegex(ValidationError, r'x should have exactly 2 items'):
+            check_tuple([check_int, check_int])('x', x)
+
+        check_tuple([check_string, check_int])('x', ('string', 42))
+
     def test_check_list(self) -> None:
         x: Any = 999
         with self.assertRaisesRegex(ValidationError, r'x is not a list'):
diff --git a/zerver/tests/test_events.py b/zerver/tests/test_events.py
index 0cb00e825a..b0ae35709b 100644
--- a/zerver/tests/test_events.py
+++ b/zerver/tests/test_events.py
@@ -139,6 +139,7 @@ from zerver.lib.validator import (
     check_list,
     check_none_or,
     check_string,
+    check_tuple,
     check_url,
     equals,
 )
@@ -1493,7 +1494,11 @@ class EventsRegisterTest(ZulipTestCase):
     def test_muted_topics_events(self) -> None:
         muted_topics_checker = self.check_events_dict([
             ('type', equals('muted_topics')),
-            ('muted_topics', check_list(check_list(sub_validator=None, length=3))),
+            ('muted_topics', check_list(check_tuple([
+                check_string,  # stream name
+                check_string,  # topic name
+                check_int,  # timestamp
+            ]))),
         ])
         stream = get_stream('Denmark', self.user_profile.realm)
         recipient = stream.recipient
diff --git a/zerver/tests/test_muting.py b/zerver/tests/test_muting.py
index 91d72ff386..818f40b788 100644
--- a/zerver/tests/test_muting.py
+++ b/zerver/tests/test_muting.py
@@ -73,7 +73,7 @@ class MutedTopicsTests(ZulipTestCase):
                 result = self.api_patch(user, url, data)
                 self.assert_json_success(result)
 
-            self.assertIn([stream.name, 'Verona3', mock_date_muted], get_topic_mutes(user))
+            self.assertIn((stream.name, 'Verona3', mock_date_muted), get_topic_mutes(user))
             self.assertTrue(topic_is_muted(user, stream.id, 'Verona3'))
             self.assertTrue(topic_is_muted(user, stream.id, 'verona3'))
 
@@ -106,12 +106,12 @@ class MutedTopicsTests(ZulipTestCase):
                 topic_name='Verona3',
                 date_muted=datetime(2020, 1, 1, tzinfo=timezone.utc),
             )
-            self.assertIn([stream.name, 'Verona3', mock_date_muted], get_topic_mutes(user))
+            self.assertIn((stream.name, 'Verona3', mock_date_muted), get_topic_mutes(user))
 
             result = self.api_patch(user, url, data)
 
             self.assert_json_success(result)
-            self.assertNotIn([stream.name, 'Verona3', mock_date_muted], get_topic_mutes(user))
+            self.assertNotIn((stream.name, 'Verona3', mock_date_muted), get_topic_mutes(user))
             self.assertFalse(topic_is_muted(user, stream.id, 'verona3'))
 
     def test_muted_topic_add_invalid(self) -> None: