diff --git a/.mypy.ini b/.mypy.ini
new file mode 100644
index 0000000..700e458
--- /dev/null
+++ b/.mypy.ini
@@ -0,0 +1,37 @@
+[mypy]
+files = aiohttp_security, demo, tests
+check_untyped_defs = True
+follow_imports_for_stubs = True
+disallow_any_decorated = True
+disallow_any_generics = True
+disallow_incomplete_defs = True
+disallow_subclassing_any = True
+disallow_untyped_calls = True
+disallow_untyped_decorators = True
+disallow_untyped_defs = True
+implicit_reexport = False
+no_implicit_optional = True
+show_error_codes = True
+strict_equality = True
+warn_incomplete_stub = True
+warn_redundant_casts = True
+warn_unreachable = True
+warn_unused_ignores = True
+disallow_any_unimported = True
+warn_return_any = True
+
+[mypy-aiohttp_security.abc.*]
+disallow_any_decorated = False
+
+[mypy-tests.*]
+disallow_any_decorated = False
+disallow_untyped_defs = False
+
+[mypy-aiopg.*]
+ignore_missing_imports = True
+
+[mypy-aioredis.*]
+ignore_missing_imports = True
+
+[mypy-passlib.*]
+ignore_missing_imports = True
diff --git a/aiohttp_security/abc.py b/aiohttp_security/abc.py
index 862abd8..0b63bb5 100644
--- a/aiohttp_security/abc.py
+++ b/aiohttp_security/abc.py
@@ -1,4 +1,8 @@
 import abc
+from enum import Enum
+from typing import Any, Optional, Union
+
+from aiohttp import web
 
 # see http://plope.com/pyramid_auth_design_api_postmortem
 
@@ -6,13 +10,14 @@ import abc
 class AbstractIdentityPolicy(metaclass=abc.ABCMeta):
 
     @abc.abstractmethod
-    async def identify(self, request):
+    async def identify(self, request: web.Request) -> Optional[str]:
         """Return the claimed identity of the user associated request or
         ``None`` if no identity can be found associated with the request."""
         pass
 
     @abc.abstractmethod
-    async def remember(self, request, response, identity, **kwargs):
+    async def remember(self, request: web.Request, response: web.StreamResponse,
+                       identity: str, **kwargs: Any) -> None:
         """Remember identity.
 
         Modify response object by filling it's headers with remembered user.
@@ -23,7 +28,7 @@ class AbstractIdentityPolicy(metaclass=abc.ABCMeta):
         pass
 
     @abc.abstractmethod
-    async def forget(self, request, response):
+    async def forget(self, request: web.Request, response: web.StreamResponse) -> None:
         """ Modify response which can be used to 'forget' the
         current identity on subsequent requests."""
         pass
@@ -32,7 +37,8 @@ class AbstractIdentityPolicy(metaclass=abc.ABCMeta):
 class AbstractAuthorizationPolicy(metaclass=abc.ABCMeta):
 
     @abc.abstractmethod
-    async def permits(self, identity, permission, context=None):
+    async def permits(self, identity: str, permission: Union[str, Enum],
+                      context: Any = None) -> bool:
         """Check user permissions.
 
         Return True if the identity is allowed the permission in the
@@ -41,7 +47,7 @@ class AbstractAuthorizationPolicy(metaclass=abc.ABCMeta):
         pass
 
     @abc.abstractmethod
-    async def authorized_userid(self, identity):
+    async def authorized_userid(self, identity: str) -> Optional[str]:
         """Retrieve authorized user id.
 
         Return the user_id of the user identified by the identity
diff --git a/aiohttp_security/api.py b/aiohttp_security/api.py
index d6a2dd5..ccf1798 100644
--- a/aiohttp_security/api.py
+++ b/aiohttp_security/api.py
@@ -1,15 +1,23 @@
 import enum
 import warnings
-from aiohttp import web
-from aiohttp_security.abc import (AbstractIdentityPolicy,
-                                  AbstractAuthorizationPolicy)
 from functools import wraps
+from typing import Any, Callable, Optional, TypeVar, Union
+
+from aiohttp import web
+from aiohttp_security.abc import AbstractAuthorizationPolicy, AbstractIdentityPolicy
 
 IDENTITY_KEY = 'aiohttp_security_identity_policy'
 AUTZ_KEY = 'aiohttp_security_autz_policy'
 
+# _AIP/_AAP are shorthand for Optional[policy] when we retrieve from request.
+_AAP = Optional[AbstractAuthorizationPolicy]
+_AIP = Optional[AbstractIdentityPolicy]
+_Handler = TypeVar('_Handler', bound=Union[Callable[[web.Request], Any],
+                                           Callable[[object, web.Request], Any]])
 
-async def remember(request, response, identity, **kwargs):
+
+async def remember(request: web.Request, response: web.StreamResponse,
+                   identity: str, **kwargs: Any) -> None:
     """Remember identity into response.
 
     The action is performed by identity_policy.remember()
@@ -30,7 +38,7 @@ async def remember(request, response, identity, **kwargs):
     await identity_policy.remember(request, response, identity, **kwargs)
 
 
-async def forget(request, response):
+async def forget(request: web.Request, response: web.StreamResponse) -> None:
     """Forget previously remembered identity.
 
     Usually it clears cookie or server-side storage to forget user
@@ -47,9 +55,9 @@ async def forget(request, response):
     await identity_policy.forget(request, response)
 
 
-async def authorized_userid(request):
-    identity_policy = request.config_dict.get(IDENTITY_KEY)
-    autz_policy = request.config_dict.get(AUTZ_KEY)
+async def authorized_userid(request: web.Request) -> Optional[str]:
+    identity_policy: _AIP = request.config_dict.get(IDENTITY_KEY)
+    autz_policy: _AAP = request.config_dict.get(AUTZ_KEY)
     if identity_policy is None or autz_policy is None:
         return None
     identity = await identity_policy.identify(request)
@@ -59,20 +67,21 @@ async def authorized_userid(request):
     return user_id
 
 
-async def permits(request, permission, context=None):
+async def permits(request: web.Request, permission: Union[str, enum.Enum],
+                  context: Any = None) -> bool:
     assert isinstance(permission, (str, enum.Enum)), permission
     assert permission
-    identity_policy = request.config_dict.get(IDENTITY_KEY)
-    autz_policy = request.config_dict.get(AUTZ_KEY)
+    identity_policy: _AIP = request.config_dict.get(IDENTITY_KEY)
+    autz_policy: _AAP = request.config_dict.get(AUTZ_KEY)
     if identity_policy is None or autz_policy is None:
         return True
     identity = await identity_policy.identify(request)
-    # non-registered user still may has some permissions
+    # non-registered user still may have some permissions
     access = await autz_policy.permits(identity, permission, context)
     return access
 
 
-async def is_anonymous(request):
+async def is_anonymous(request: web.Request) -> bool:
     """Check if user is anonymous.
 
     User is considered anonymous if there is not identity
@@ -87,7 +96,7 @@ async def is_anonymous(request):
     return False
 
 
-async def check_authorized(request):
+async def check_authorized(request: web.Request) -> str:
     """Checker that raises HTTPUnauthorized for anonymous users.
     """
     userid = await authorized_userid(request)
@@ -96,31 +105,32 @@ async def check_authorized(request):
     return userid
 
 
-def login_required(fn):
+def login_required(fn: _Handler) -> _Handler:
     """Decorator that restrict access only for authorized users.
 
     User is considered authorized if authorized_userid
     returns some value.
     """
     @wraps(fn)
-    async def wrapped(*args, **kwargs):
+    async def wrapped(*args: Union[object, web.Request]) -> Any:
         request = args[-1]
-        if not isinstance(request, web.BaseRequest):
+        if not isinstance(request, web.Request):
             msg = ("Incorrect decorator usage. "
                    "Expecting `def handler(request)` "
                    "or `def handler(self, request)`.")
             raise RuntimeError(msg)
 
         await check_authorized(request)
-        return await fn(*args, **kwargs)
+        return await fn(*args)  # type: ignore[arg-type]
 
     warnings.warn("login_required decorator is deprecated, "
                   "use check_authorized instead",
                   DeprecationWarning)
-    return wrapped
+    return wrapped  # type: ignore[return-value]
 
 
-async def check_permission(request, permission, context=None):
+async def check_permission(request: web.Request, permission: Union[str, enum.Enum],
+                           context: Any = None) -> None:
     """Checker that passes only to authoraised users with given permission.
 
     If user is not authorized - raises HTTPUnauthorized,
@@ -134,10 +144,7 @@ async def check_permission(request, permission, context=None):
         raise web.HTTPForbidden()
 
 
-def has_permission(
-    permission,
-    context=None,
-):
+def has_permission(permission: Union[str, enum.Enum], context: Any = None):  # type: ignore
     """Decorator that restricts access only for authorized users
     with correct permissions.
 
@@ -145,11 +152,11 @@ def has_permission(
     if user is authorized and does not have permission -
     raises HTTPForbidden.
     """
-    def wrapper(fn):
+    def wrapper(fn):  # type: ignore
         @wraps(fn)
-        async def wrapped(*args, **kwargs):
+        async def wrapped(*args, **kwargs):  # type: ignore
             request = args[-1]
-            if not isinstance(request, web.BaseRequest):
+            if not isinstance(request, web.Request):
                 msg = ("Incorrect decorator usage. "
                        "Expecting `def handler(request)` "
                        "or `def handler(self, request)`.")
@@ -166,7 +173,8 @@ def has_permission(
     return wrapper
 
 
-def setup(app, identity_policy, autz_policy):
+def setup(app: web.Application, identity_policy: AbstractIdentityPolicy,
+          autz_policy: AbstractAuthorizationPolicy) -> None:
     assert isinstance(identity_policy, AbstractIdentityPolicy), identity_policy
     assert isinstance(autz_policy, AbstractAuthorizationPolicy), autz_policy
 
diff --git a/aiohttp_security/cookies_identity.py b/aiohttp_security/cookies_identity.py
index 3822ef9..f20c422 100644
--- a/aiohttp_security/cookies_identity.py
+++ b/aiohttp_security/cookies_identity.py
@@ -5,28 +5,32 @@ more handy.
 
 """
 
+from aiohttp import web
+from typing import Any, NewType, Optional, Union, cast
+
 from .abc import AbstractIdentityPolicy
 
-
-sentinel = object()
+_Sentinel = NewType('_Sentinel', object)
+sentinel = _Sentinel(object())
 
 
 class CookiesIdentityPolicy(AbstractIdentityPolicy):
 
-    def __init__(self):
+    def __init__(self) -> None:
         self._cookie_name = 'AIOHTTP_SECURITY'
         self._max_age = 30 * 24 * 3600
 
-    async def identify(self, request):
-        identity = request.cookies.get(self._cookie_name)
-        return identity
+    async def identify(self, request: web.Request) -> Optional[str]:
+        return request.cookies.get(self._cookie_name)
 
-    async def remember(self, request, response, identity, max_age=sentinel,
-                       **kwargs):
+    async def remember(self, request: web.Request, response: web.StreamResponse,
+                       identity: str, max_age: Union[_Sentinel, Optional[int]] = sentinel,
+                       **kwargs: Any) -> None:
         if max_age is sentinel:
             max_age = self._max_age
+        max_age = cast(Optional[int], max_age)
         response.set_cookie(self._cookie_name, identity,
                             max_age=max_age, **kwargs)
 
-    async def forget(self, request, response):
+    async def forget(self, request: web.Request, response: web.StreamResponse) -> None:
         response.del_cookie(self._cookie_name)
diff --git a/aiohttp_security/jwt_identity.py b/aiohttp_security/jwt_identity.py
index bd6ffe7..e456007 100644
--- a/aiohttp_security/jwt_identity.py
+++ b/aiohttp_security/jwt_identity.py
@@ -2,12 +2,17 @@
 
 """
 
+from typing import Optional
+
+from aiohttp import web
+
 from .abc import AbstractIdentityPolicy
 
 try:
     import jwt
+    HAS_JWT = True
 except ImportError:  # pragma: no cover
-    jwt = None
+    HAS_JWT = False
 
 
 AUTH_HEADER_NAME = 'Authorization'
@@ -15,21 +20,21 @@ AUTH_SCHEME = 'Bearer '
 
 
 class JWTIdentityPolicy(AbstractIdentityPolicy):
-    def __init__(self, secret, algorithm='HS256'):
-        if jwt is None:
+    def __init__(self, secret: str, algorithm: str = 'HS256'):
+        if not HAS_JWT:
             raise RuntimeError('Please install `PyJWT`')
         self.secret = secret
         self.algorithm = algorithm
 
-    async def identify(self, request):
+    async def identify(self, request: web.Request) -> Optional[str]:
         header_identity = request.headers.get(AUTH_HEADER_NAME)
 
         if header_identity is None:
-            return
+            return None
 
         if not header_identity.startswith(AUTH_SCHEME):
             raise ValueError('Invalid authorization scheme. ' +
-                             'Should be `Bearer <token>`')
+                             'Should be `{}<token>`'.format(AUTH_SCHEME))
 
         token = header_identity.split(' ')[1].strip()
 
@@ -38,8 +43,9 @@ class JWTIdentityPolicy(AbstractIdentityPolicy):
                               algorithms=[self.algorithm])
         return identity
 
-    async def remember(self, *args, **kwargs):  # pragma: no cover
+    async def remember(self, request: web.Request, response: web.StreamResponse,
+                       identity: str, **kwargs: None) -> None:
         pass
 
-    async def forget(self, request, response):  # pragma: no cover
+    async def forget(self, request: web.Request, response: web.StreamResponse) -> None:
         pass
diff --git a/aiohttp_security/py.typed b/aiohttp_security/py.typed
new file mode 100644
index 0000000..e69de29
diff --git a/aiohttp_security/session_identity.py b/aiohttp_security/session_identity.py
index 13d197a..33c5ef2 100644
--- a/aiohttp_security/session_identity.py
+++ b/aiohttp_security/session_identity.py
@@ -4,6 +4,7 @@ aiohttp_session.setup() should be called on application initialization
 to configure aiohttp_session properly.
 """
 
+from aiohttp import web
 try:
     from aiohttp_session import get_session
     HAS_AIOHTTP_SESSION = True
@@ -15,21 +16,22 @@ from .abc import AbstractIdentityPolicy
 
 class SessionIdentityPolicy(AbstractIdentityPolicy):
 
-    def __init__(self, session_key='AIOHTTP_SECURITY'):
+    def __init__(self, session_key: str = 'AIOHTTP_SECURITY'):
         self._session_key = session_key
 
         if not HAS_AIOHTTP_SESSION:  # pragma: no cover
             raise ImportError(
                 'SessionIdentityPolicy requires `aiohttp_session`')
 
-    async def identify(self, request):
+    async def identify(self, request: web.Request) -> str:
         session = await get_session(request)
         return session.get(self._session_key)
 
-    async def remember(self, request, response, identity, **kwargs):
+    async def remember(self, request: web.Request, response: web.StreamResponse,
+                       identity: str, **kwargs: None) -> None:
         session = await get_session(request)
         session[self._session_key] = identity
 
-    async def forget(self, request, response):
+    async def forget(self, request: web.Request, response: web.StreamResponse) -> None:
         session = await get_session(request)
         session.pop(self._session_key, None)
diff --git a/demo/__init__.py b/demo/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/demo/database_auth/__init__.py b/demo/database_auth/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/demo/database_auth/db_auth.py b/demo/database_auth/db_auth.py
index 72b1ad2..5eaf04a 100644
--- a/demo/database_auth/db_auth.py
+++ b/demo/database_auth/db_auth.py
@@ -1,5 +1,7 @@
-import sqlalchemy as sa
+from enum import Enum
+from typing import Any, Optional, Union
 
+import sqlalchemy as sa
 from aiohttp_security.abc import AbstractAuthorizationPolicy
 from passlib.hash import sha256_crypt
 
@@ -7,13 +9,13 @@ from . import db
 
 
 class DBAuthorizationPolicy(AbstractAuthorizationPolicy):
-    def __init__(self, dbengine):
+    def __init__(self, dbengine: Any):
         self.dbengine = dbengine
 
-    async def authorized_userid(self, identity):
+    async def authorized_userid(self, identity: str) -> Optional[str]:
         async with self.dbengine.acquire() as conn:
             where = sa.and_(db.users.c.login == identity,
-                            sa.not_(db.users.c.disabled))
+                            sa.not_(db.users.c.disabled))  # type: ignore[no-untyped-call]
             query = db.users.count().where(where)
             ret = await conn.scalar(query)
             if ret:
@@ -21,13 +23,11 @@ class DBAuthorizationPolicy(AbstractAuthorizationPolicy):
             else:
                 return None
 
-    async def permits(self, identity, permission, context=None):
-        if identity is None:
-            return False
-
+    async def permits(self, identity: str, permission: Union[str, Enum],
+                      context: None = None) -> bool:
         async with self.dbengine.acquire() as conn:
             where = sa.and_(db.users.c.login == identity,
-                            sa.not_(db.users.c.disabled))
+                            sa.not_(db.users.c.disabled))  # type: ignore[no-untyped-call]
             query = db.users.select().where(where)
             ret = await conn.execute(query)
             user = await ret.fetchone()
@@ -49,14 +49,14 @@ class DBAuthorizationPolicy(AbstractAuthorizationPolicy):
             return False
 
 
-async def check_credentials(db_engine, username, password):
+async def check_credentials(db_engine: Any, username: str, password: str) -> bool:
     async with db_engine.acquire() as conn:
         where = sa.and_(db.users.c.login == username,
-                        sa.not_(db.users.c.disabled))
+                        sa.not_(db.users.c.disabled))  # type: ignore[no-untyped-call]
         query = db.users.select().where(where)
         ret = await conn.execute(query)
         user = await ret.fetchone()
         if user is not None:
             hashed = user[2]
-            return sha256_crypt.verify(password, hashed)
+            return sha256_crypt.verify(password, hashed)  # type: ignore[no-any-return]
     return False
diff --git a/demo/database_auth/handlers.py b/demo/database_auth/handlers.py
index 0cc9484..19a2bf9 100644
--- a/demo/database_auth/handlers.py
+++ b/demo/database_auth/handlers.py
@@ -1,4 +1,5 @@
 from textwrap import dedent
+from typing import NoReturn
 
 from aiohttp import web
 
@@ -27,7 +28,7 @@ class Web(object):
             </body>
     """)
 
-    async def index(self, request):
+    async def index(self, request: web.Request) -> web.Response:
         username = await authorized_userid(request)
         if username:
             template = self.index_template.format(
@@ -37,37 +38,41 @@ class Web(object):
         response = web.Response(body=template.encode())
         return response
 
-    async def login(self, request):
-        response = web.HTTPFound('/')
+    async def login(self, request: web.Request) -> NoReturn:
+        invalid_resp = web.HTTPUnauthorized(body=b'Invalid username/password combination')
         form = await request.post()
         login = form.get('login')
         password = form.get('password')
-        db_engine = request.app.db_engine
+        db_engine = request.app['db_engine']
+
+        if not (isinstance(login, str) and isinstance(password, str)):
+            raise invalid_resp
+
         if await check_credentials(db_engine, login, password):
+            response = web.HTTPFound('/')
             await remember(request, response, login)
             raise response
 
-        raise web.HTTPUnauthorized(
-            body=b'Invalid username/password combination')
+        raise invalid_resp
 
-    async def logout(self, request):
+    async def logout(self, request: web.Request) -> web.Response:
         await check_authorized(request)
         response = web.Response(body=b'You have been logged out')
         await forget(request, response)
         return response
 
-    async def internal_page(self, request):
+    async def internal_page(self, request: web.Request) -> web.Response:
         await check_permission(request, 'public')
         response = web.Response(
             body=b'This page is visible for all registered users')
         return response
 
-    async def protected_page(self, request):
+    async def protected_page(self, request: web.Request) -> web.Response:
         await check_permission(request, 'protected')
         response = web.Response(body=b'You are on protected page')
         return response
 
-    def configure(self, app):
+    def configure(self, app: web.Application) -> None:
         router = app.router
         router.add_route('GET', '/', self.index, name='index')
         router.add_route('POST', '/login', self.login, name='login')
diff --git a/demo/database_auth/main.py b/demo/database_auth/main.py
index 822df44..b6b81d8 100644
--- a/demo/database_auth/main.py
+++ b/demo/database_auth/main.py
@@ -1,4 +1,5 @@
 import asyncio
+from typing import Any, Tuple
 
 from aiohttp import web
 from aiohttp_session import setup as setup_session
@@ -13,14 +14,14 @@ from demo.database_auth.db_auth import DBAuthorizationPolicy
 from demo.database_auth.handlers import Web
 
 
-async def init(loop):
+async def init(loop: asyncio.AbstractEventLoop) -> Tuple[Any, ...]:
     redis_pool = await create_pool(('localhost', 6379))
     db_engine = await create_engine(user='aiohttp_security',
                                     password='aiohttp_security',
                                     database='aiohttp_security',
                                     host='127.0.0.1')
     app = web.Application()
-    app.db_engine = db_engine
+    app['db_engine'] = db_engine
     setup_session(app, RedisStorage(redis_pool))
     setup_security(app,
                    SessionIdentityPolicy(),
@@ -35,7 +36,7 @@ async def init(loop):
     return srv, app, handler
 
 
-async def finalize(srv, app, handler):
+async def finalize(srv: Any, app: Any, handler: Any) -> None:
     sock = srv.sockets[0]
     app.loop.remove_reader(sock.fileno())
     sock.close()
@@ -46,7 +47,7 @@ async def finalize(srv, app, handler):
     await app.finish()
 
 
-def main():
+def main() -> None:
     loop = asyncio.get_event_loop()
     srv, app, handler = loop.run_until_complete(init(loop))
     try:
diff --git a/demo/dictionary_auth/__init__.py b/demo/dictionary_auth/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/demo/dictionary_auth/authz.py b/demo/dictionary_auth/authz.py
index 0f9baae..57ef52a 100644
--- a/demo/dictionary_auth/authz.py
+++ b/demo/dictionary_auth/authz.py
@@ -1,20 +1,25 @@
+from enum import Enum
+from typing import Dict, Optional, Union
+
 from aiohttp_security.abc import AbstractAuthorizationPolicy
 
+from .users import User
+
 
 class DictionaryAuthorizationPolicy(AbstractAuthorizationPolicy):
-    def __init__(self, user_map):
+    def __init__(self, user_map: Dict[str, User]):
         super().__init__()
         self.user_map = user_map
 
-    async def authorized_userid(self, identity):
+    async def authorized_userid(self, identity: str) -> Optional[str]:
         """Retrieve authorized user id.
         Return the user_id of the user identified by the identity
         or 'None' if no user exists related to the identity.
         """
-        if identity in self.user_map:
-            return identity
+        return identity if identity in self.user_map else None
 
-    async def permits(self, identity, permission, context=None):
+    async def permits(self, identity: str, permission: Union[str, Enum],
+                      context: None = None) -> bool:
         """Check user permissions.
         Return True if the identity is allowed the permission in the
         current context, else return False.
@@ -26,7 +31,7 @@ class DictionaryAuthorizationPolicy(AbstractAuthorizationPolicy):
         return permission in user.permissions
 
 
-async def check_credentials(user_map, username, password):
+async def check_credentials(user_map: Dict[str, User], username: str, password: str) -> bool:
     user = user_map.get(username)
     if not user:
         return False
diff --git a/demo/dictionary_auth/handlers.py b/demo/dictionary_auth/handlers.py
index 6c19bab..e558715 100644
--- a/demo/dictionary_auth/handlers.py
+++ b/demo/dictionary_auth/handlers.py
@@ -1,4 +1,5 @@
 from textwrap import dedent
+from typing import Dict, NoReturn
 
 from aiohttp import web
 
@@ -8,6 +9,7 @@ from aiohttp_security import (
 )
 
 from .authz import check_credentials
+from .users import User
 
 
 index_template = dedent("""
@@ -27,7 +29,7 @@ index_template = dedent("""
 """)
 
 
-async def index(request):
+async def index(request: web.Request) -> web.Response:
     username = await authorized_userid(request)
     if username:
         template = index_template.format(
@@ -40,22 +42,26 @@ async def index(request):
     )
 
 
-async def login(request):
-    response = web.HTTPFound('/')
+async def login(request: web.Request) -> NoReturn:
+    user_map: Dict[str, User] = request.app['user_map']
+    invalid_response = web.HTTPUnauthorized(body='Invalid username / password combination')
     form = await request.post()
     username = form.get('username')
     password = form.get('password')
 
-    verified = await check_credentials(
-        request.app.user_map, username, password)
+    if not (isinstance(username, str) and isinstance(password, str)):
+        raise invalid_response
+
+    verified = await check_credentials(user_map, username, password)
     if verified:
+        response = web.HTTPFound('/')
         await remember(request, response, username)
-        return response
+        raise response
 
-    return web.HTTPUnauthorized(body='Invalid username / password combination')
+    raise invalid_response
 
 
-async def logout(request):
+async def logout(request: web.Request) -> web.Response:
     await check_authorized(request)
     response = web.Response(
         text='You have been logged out',
@@ -65,7 +71,7 @@ async def logout(request):
     return response
 
 
-async def internal_page(request):
+async def internal_page(request: web.Request) -> web.Response:
     await check_permission(request, 'public')
     response = web.Response(
         text='This page is visible for all registered users',
@@ -74,7 +80,7 @@ async def internal_page(request):
     return response
 
 
-async def protected_page(request):
+async def protected_page(request: web.Request) -> web.Response:
     await check_permission(request, 'protected')
     response = web.Response(
         text='You are on protected page',
@@ -83,7 +89,7 @@ async def protected_page(request):
     return response
 
 
-def configure_handlers(app):
+def configure_handlers(app: web.Application) -> None:
     router = app.router
     router.add_get('/', index, name='index')
     router.add_post('/login', login, name='login')
diff --git a/demo/dictionary_auth/main.py b/demo/dictionary_auth/main.py
index b4fe2b4..0bd5f1a 100644
--- a/demo/dictionary_auth/main.py
+++ b/demo/dictionary_auth/main.py
@@ -11,9 +11,9 @@ from demo.dictionary_auth.handlers import configure_handlers
 from demo.dictionary_auth.users import user_map
 
 
-def make_app():
+def make_app() -> web.Application:
     app = web.Application()
-    app.user_map = user_map
+    app['user_map'] = user_map
     configure_handlers(app)
 
     # secret_key must be 32 url-safe base64-encoded bytes
diff --git a/demo/dictionary_auth/users.py b/demo/dictionary_auth/users.py
index 967b2bb..65a9aa5 100644
--- a/demo/dictionary_auth/users.py
+++ b/demo/dictionary_auth/users.py
@@ -1,6 +1,11 @@
-from collections import namedtuple
+from typing import NamedTuple, Tuple
+
+
+class User(NamedTuple):
+    username: str
+    password: str
+    permissions: Tuple[str, ...]
 
-User = namedtuple('User', ['username', 'password', 'permissions'])
 
 user_map = {
     user.username: user for user in [
diff --git a/demo/simple_example_auth.py b/demo/simple_example_auth.py
index 5b4b82d..a613518 100644
--- a/demo/simple_example_auth.py
+++ b/demo/simple_example_auth.py
@@ -1,3 +1,6 @@
+from enum import Enum
+from typing import NoReturn, Optional, Union
+
 from aiohttp import web
 from aiohttp_session import SimpleCookieStorage, session_middleware
 from aiohttp_security import check_permission, \
@@ -11,15 +14,15 @@ from aiohttp_security.abc import AbstractAuthorizationPolicy
 # For more complicated authorization policies see examples
 # in the 'demo' directory.
 class SimpleJack_AuthorizationPolicy(AbstractAuthorizationPolicy):
-    async def authorized_userid(self, identity):
+    async def authorized_userid(self, identity: str) -> Optional[str]:
         """Retrieve authorized user id.
         Return the user_id of the user identified by the identity
         or 'None' if no user exists related to the identity.
         """
-        if identity == 'jack':
-            return identity
+        return identity if identity == 'jack' else None
 
-    async def permits(self, identity, permission, context=None):
+    async def permits(self, identity: str, permission: Union[str, Enum],
+                      context: None = None) -> bool:
         """Check user permissions.
         Return True if the identity is allowed the permission
         in the current context, else return False.
@@ -27,7 +30,7 @@ class SimpleJack_AuthorizationPolicy(AbstractAuthorizationPolicy):
         return identity == 'jack' and permission in ('listen',)
 
 
-async def handler_root(request):
+async def handler_root(request: web.Request) -> web.Response:
     is_logged = not await is_anonymous(request)
     return web.Response(text='''<html><head></head><body>
             Hello, I'm Jack, I'm {logged} logged in.<br /><br />
@@ -42,29 +45,29 @@ async def handler_root(request):
         ), content_type='text/html')
 
 
-async def handler_login_jack(request):
+async def handler_login_jack(request: web.Request) -> NoReturn:
     redirect_response = web.HTTPFound('/')
     await remember(request, redirect_response, 'jack')
     raise redirect_response
 
 
-async def handler_logout(request):
+async def handler_logout(request: web.Request) -> NoReturn:
     redirect_response = web.HTTPFound('/')
     await forget(request, redirect_response)
     raise redirect_response
 
 
-async def handler_listen(request):
+async def handler_listen(request: web.Request) -> web.Response:
     await check_permission(request, 'listen')
     return web.Response(body="I can listen!")
 
 
-async def handler_speak(request):
+async def handler_speak(request: web.Request) -> web.Response:
     await check_permission(request, 'speak')
     return web.Response(body="I can speak!")
 
 
-async def make_app():
+async def make_app() -> web.Application:
     #
     # WARNING!!!
     # Never use SimpleCookieStorage on production!!!
diff --git a/tests/__init__.py b/tests/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/tests/test_jwt_identity.py b/tests/test_jwt_identity.py
index 813deac..a01e815 100644
--- a/tests/test_jwt_identity.py
+++ b/tests/test_jwt_identity.py
@@ -67,7 +67,7 @@ async def test_identify_broken_scheme(loop, make_token, aiohttp_client):
         try:
             await policy.identify(request)
         except ValueError as exc:
-            raise web.HTTPBadRequest(reason=exc)
+            raise web.HTTPBadRequest(reason=str(exc))
 
         return web.Response()