diff --git a/corporate/lib/stripe.py b/corporate/lib/stripe.py
index 3ab4917dd1..dce2b5fe04 100644
--- a/corporate/lib/stripe.py
+++ b/corporate/lib/stripe.py
@@ -612,7 +612,7 @@ def is_free_trial_offer_enabled() -> bool:
     return settings.FREE_TRIAL_DAYS not in (None, 0)
 
 
-def ensure_realm_does_not_have_active_plan(realm: Customer) -> None:
+def ensure_realm_does_not_have_active_plan(realm: Realm) -> None:
     if get_current_plan_by_realm(realm) is not None:
         # Unlikely race condition from two people upgrading (clicking "Make payment")
         # at exactly the same time. Doesn't fully resolve the race condition, but having
diff --git a/zerver/forms.py b/zerver/forms.py
index b8f00f1e60..79b9c30f99 100644
--- a/zerver/forms.py
+++ b/zerver/forms.py
@@ -296,7 +296,7 @@ class ZulipPasswordResetForm(PasswordResetForm):
         use_https: bool = False,
         token_generator: PasswordResetTokenGenerator = default_token_generator,
         from_email: Optional[str] = None,
-        request: HttpRequest = None,
+        request: Optional[HttpRequest] = None,
         html_email_template_name: Optional[str] = None,
         extra_email_context: Optional[Dict[str, Any]] = None,
     ) -> None:
@@ -312,6 +312,9 @@ class ZulipPasswordResetForm(PasswordResetForm):
         are an artifact of using Django's password reset framework).
         """
         email = self.cleaned_data["email"]
+        # The form is only used in zerver.views.auth.password_rest, we know that
+        # the request must not be None
+        assert request is not None
 
         realm = get_realm(get_subdomain(request))
 
diff --git a/zerver/lib/test_classes.py b/zerver/lib/test_classes.py
index 0390210ccc..260cc47e2d 100644
--- a/zerver/lib/test_classes.py
+++ b/zerver/lib/test_classes.py
@@ -129,12 +129,12 @@ class UploadSerializeMixin(SerializeMixin):
     lockfile = "var/upload_lock"
 
     @classmethod
-    def setUpClass(cls: Any, *args: Any, **kwargs: Any) -> None:
+    def setUpClass(cls: Any) -> None:
         if not os.path.exists(cls.lockfile):
             with open(cls.lockfile, "w"):  # nocoverage - rare locking case
                 pass
 
-        super().setUpClass(*args, **kwargs)
+        super().setUpClass()
 
 
 # We could be more specific about which arguments are bool (Django's
@@ -1659,9 +1659,9 @@ You can fix this by adding "{complete_event_type}" to ALL_EVENT_TYPES for this w
         content_type: Optional[str] = "application/json",
         expect_noop: bool = False,
         **kwargs: ClientArg,
-    ) -> "TestHttpResponse":
+    ) -> None:
         kwargs["HTTP_AUTHORIZATION"] = self.encode_user(user)
-        return self.check_webhook(
+        self.check_webhook(
             fixture_name, expected_topic, expected_message, content_type, expect_noop, **kwargs
         )
 
diff --git a/zerver/migrations/0386_fix_attachment_caches.py b/zerver/migrations/0386_fix_attachment_caches.py
index 27c9af78e1..58a8dcddb5 100644
--- a/zerver/migrations/0386_fix_attachment_caches.py
+++ b/zerver/migrations/0386_fix_attachment_caches.py
@@ -1,5 +1,7 @@
 # Generated by Django 3.2.12 on 2022-03-23 04:32
 
+from typing import Type
+
 from django.db import migrations, models
 from django.db.backends.postgresql.schema import BaseDatabaseSchemaEditor
 from django.db.migrations.state import StateApps
@@ -14,7 +16,9 @@ def fix_attachment_caches(apps: StateApps, schema_editor: BaseDatabaseSchemaEdit
 
     BATCH_SIZE = 10000
 
-    def update_batch(attachment_model: Model, message_model: Model, lower_bound: int) -> None:
+    def update_batch(
+        attachment_model: Type[Model], message_model: Type[Model], lower_bound: int
+    ) -> None:
         attachment_model.objects.filter(
             id__gt=lower_bound, id__lte=lower_bound + BATCH_SIZE
         ).update(
diff --git a/zerver/views/upload.py b/zerver/views/upload.py
index 031e17f542..5dff4666f5 100644
--- a/zerver/views/upload.py
+++ b/zerver/views/upload.py
@@ -74,7 +74,7 @@ def serve_local(
 
 def serve_file_download_backend(
     request: HttpRequest, user_profile: UserProfile, realm_id_str: str, filename: str
-) -> HttpRequest:
+) -> HttpResponse:
     return serve_file(request, user_profile, realm_id_str, filename, url_only=False, download=True)