diff --git a/cura/API/Account.py b/cura/API/Account.py
index fa42c3c44d..9f1184a0a0 100644
--- a/cura/API/Account.py
+++ b/cura/API/Account.py
@@ -74,14 +74,14 @@ class Account(QObject):
         self._application = application
         self._new_cloud_printers_detected = False
 
-        self._error_message = None  # type: Optional[Message]
+        self._error_message: Optional[Message] = None
         self._logged_in = False
-        self._user_profile = None  # type: Optional[UserProfile]
+        self._user_profile: Optional[UserProfile] = None
         self._additional_rights: Dict[str, Any] = {}
         self._sync_state = SyncState.IDLE
         self._manual_sync_enabled = False
         self._update_packages_enabled = False
-        self._update_packages_action = None  # type: Optional[Callable]
+        self._update_packages_action: Optional[Callable] = None
         self._last_sync_str = "-"
 
         self._callback_port = 32118
@@ -107,7 +107,7 @@ class Account(QObject):
         self._update_timer.setSingleShot(True)
         self._update_timer.timeout.connect(self.sync)
 
-        self._sync_services = {}  # type: Dict[str, int]
+        self._sync_services: Dict[str, int] = {}
         """contains entries "service_name" : SyncState"""
 
     def initialize(self) -> None:
diff --git a/cura/OAuth2/AuthorizationRequestHandler.py b/cura/OAuth2/AuthorizationRequestHandler.py
index ff01969c50..59b3bafa98 100644
--- a/cura/OAuth2/AuthorizationRequestHandler.py
+++ b/cura/OAuth2/AuthorizationRequestHandler.py
@@ -25,11 +25,11 @@ class AuthorizationRequestHandler(BaseHTTPRequestHandler):
         super().__init__(request, client_address, server)
 
         # These values will be injected by the HTTPServer that this handler belongs to.
-        self.authorization_helpers = None  # type: Optional[AuthorizationHelpers]
-        self.authorization_callback = None  # type: Optional[Callable[[AuthenticationResponse], None]]
-        self.verification_code = None  # type: Optional[str]
+        self.authorization_helpers: Optional[AuthorizationHelpers] = None
+        self.authorization_callback: Optional[Callable[[AuthenticationResponse], None]] = None
+        self.verification_code: Optional[str] = None
 
-        self.state = None  # type: Optional[str]
+        self.state: Optional[str] = None
 
     # CURA-6609: Some browser seems to issue a HEAD instead of GET request as the callback.
     def do_HEAD(self) -> None:
diff --git a/cura/OAuth2/AuthorizationService.py b/cura/OAuth2/AuthorizationService.py
index 0884ec8901..03d1640659 100644
--- a/cura/OAuth2/AuthorizationService.py
+++ b/cura/OAuth2/AuthorizationService.py
@@ -42,13 +42,13 @@ class AuthorizationService:
         self._settings = settings
         self._auth_helpers = AuthorizationHelpers(settings)
         self._auth_url = "{}/authorize".format(self._settings.OAUTH_SERVER_URL)
-        self._auth_data = None  # type: Optional[AuthenticationResponse]
-        self._user_profile = None  # type: Optional["UserProfile"]
+        self._auth_data: Optional[AuthenticationResponse] = None
+        self._user_profile: Optional["UserProfile"] = None
         self._preferences = preferences
         self._server = LocalAuthorizationServer(self._auth_helpers, self._onAuthStateChanged, daemon=True)
         self._currently_refreshing_token = False  # Whether we are currently in the process of refreshing auth. Don't make new requests while busy.
 
-        self._unable_to_get_data_message = None  # type: Optional[Message]
+        self._unable_to_get_data_message: Optional[Message] = None
 
         self.onAuthStateChanged.connect(self._authChanged)