diff --git a/corporate/tests/test_stripe.py b/corporate/tests/test_stripe.py
index e7ca327a5c..34413a5a2d 100644
--- a/corporate/tests/test_stripe.py
+++ b/corporate/tests/test_stripe.py
@@ -622,7 +622,7 @@ class StripeTestCase(ZulipTestCase):
         free_trial: bool,
     ) -> None:
         class StripeMock(Mock):
-            def __init__(self, depth: int = 1):
+            def __init__(self, depth: int = 1) -> None:
                 super().__init__(spec=stripe.Card)
                 self.id = "id"
                 self.created = "1000"
diff --git a/zerver/lib/cache.py b/zerver/lib/cache.py
index 90f6902b27..f2f8c3c8b9 100644
--- a/zerver/lib/cache.py
+++ b/zerver/lib/cache.py
@@ -748,7 +748,7 @@ def flush_submessage(*, instance: "SubMessage", **kwargs: object) -> None:
 class IgnoreUnhashableLruCacheWrapper(Generic[ParamT, ReturnT]):
     def __init__(
         self, function: Callable[ParamT, ReturnT], cached_function: "_lru_cache_wrapper[ReturnT]"
-    ):
+    ) -> None:
         self.key_prefix = KEY_PREFIX
         self.function = function
         self.cached_function = cached_function
diff --git a/zerver/lib/markdown/__init__.py b/zerver/lib/markdown/__init__.py
index 2e7ec3c613..506d80cf53 100644
--- a/zerver/lib/markdown/__init__.py
+++ b/zerver/lib/markdown/__init__.py
@@ -386,7 +386,7 @@ class ResultWithFamily(Generic[T]):
     family: ElementFamily
     result: T
 
-    def __init__(self, family: ElementFamily, result: T):
+    def __init__(self, family: ElementFamily, result: T) -> None:
         self.family = family
         self.result = result
 
@@ -395,7 +395,7 @@ class ElementPair:
     parent: Optional["ElementPair"]
     value: Element
 
-    def __init__(self, parent: Optional["ElementPair"], value: Element):
+    def __init__(self, parent: Optional["ElementPair"], value: Element) -> None:
         self.parent = parent
         self.value = value
 
diff --git a/zerver/lib/test_fixtures.py b/zerver/lib/test_fixtures.py
index ff6ac2ec68..e659c748ba 100644
--- a/zerver/lib/test_fixtures.py
+++ b/zerver/lib/test_fixtures.py
@@ -68,7 +68,7 @@ def migration_paths() -> List[str]:
 
 
 class Database:
-    def __init__(self, platform: str, database_name: str, settings: str):
+    def __init__(self, platform: str, database_name: str, settings: str) -> None:
         self.database_name = database_name
         self.settings = settings
         self.digest_name = "db_files_hash_for_" + platform