diff --git a/src/whitenoise/runserver_nostatic/management/commands/runserver.py b/src/whitenoise/runserver_nostatic/management/commands/runserver.py
index 484b1442..83f0f65f 100644
--- a/src/whitenoise/runserver_nostatic/management/commands/runserver.py
+++ b/src/whitenoise/runserver_nostatic/management/commands/runserver.py
@@ -8,24 +8,29 @@
 """
 from __future__ import annotations
 
+import argparse
 from importlib import import_module
+from typing import Generator
 
 from django.apps import apps
+from django.core.management import BaseCommand
 
 
-def get_next_runserver_command():
+def get_next_runserver_command() -> type[BaseCommand]:
     """
     Return the next highest priority "runserver" command class
     """
     for app_name in get_lower_priority_apps():
         module_path = "%s.management.commands.runserver" % app_name
         try:
-            return import_module(module_path).Command
+            klass: type[BaseCommand] = import_module(module_path).Command
+            return klass
         except (ImportError, AttributeError):
             pass
+    raise ValueError("No lower priority app has a 'runserver' command")
 
 
-def get_lower_priority_apps():
+def get_lower_priority_apps() -> Generator[str, None, None]:
     """
     Yield all app module names below the current app in the INSTALLED_APPS list
     """
@@ -42,11 +47,12 @@ def get_lower_priority_apps():
 RunserverCommand = get_next_runserver_command()
 
 
-class Command(RunserverCommand):
-    def add_arguments(self, parser):
+class Command(RunserverCommand):  # type: ignore [misc,valid-type]
+    def add_arguments(self, parser: argparse.ArgumentParser) -> None:
         super().add_arguments(parser)
         if parser.get_default("use_static_handler") is True:
             parser.set_defaults(use_static_handler=False)
+            assert parser.description is not None
             parser.description += (
                 "\n(Wrapped by 'whitenoise.runserver_nostatic' to always"
                 " enable '--nostatic')"