diff --git a/protocol.py b/protocol.py
index 9f5ca959..e6184a5e 100644
--- a/protocol.py
+++ b/protocol.py
@@ -1,5 +1,4 @@
-# edmc: protocol handler for cAPI authorisation
-
+"""protocol handler for cAPI authorisation."""
 
 import sys
 import threading
@@ -30,20 +29,20 @@ if sys.platform == 'win32':
 class GenericProtocolHandler:
     """Base Protocol Handler."""
 
-    def __init__(self):
+    def __init__(self) -> None:
         self.redirect = protocolhandler_redirect  # Base redirection URL
-        self.master = None
+        self.master: 'tkinter.Tk' = None  # type: ignore
         self.lastpayload = None
 
-    def start(self, master: 'tkinter.Tk'):
+    def start(self, master: 'tkinter.Tk') -> None:
         """Start Protocol Handler."""
         self.master = master
 
-    def close(self):
+    def close(self) -> None:
         """Stop / Close Protocol Handler."""
         pass
 
-    def event(self, url):
+    def event(self, url) -> None:
         """Generate an auth event."""
         self.lastpayload = url
 
@@ -69,13 +68,13 @@ if sys.platform == 'darwin' and getattr(sys, 'frozen', False):  # noqa: C901 # i
 
         POLL = 100  # ms
 
-        def start(self, master):
+        def start(self, master: 'tkinter.Tk') -> None:
             """Start Protocol Handler."""
             GenericProtocolHandler.start(self, master)
             self.lasturl: Optional[str] = None
             self.eventhandler = EventHandler.alloc().init()
 
-        def poll(self):
+        def poll(self) -> None:
             """Poll event until URL is updated."""
             # No way of signalling to Tkinter from within the callback handler block that doesn't cause Python to crash,
             # so poll. TODO: Resolved?
@@ -86,7 +85,7 @@ if sys.platform == 'darwin' and getattr(sys, 'frozen', False):  # noqa: C901 # i
     class EventHandler(NSObject):
         """Handle NSAppleEventManager IPC stuff."""
 
-        def init(self):
+        def init(self) -> None:
             """
             Init method for handler.
 
@@ -101,7 +100,7 @@ if sys.platform == 'darwin' and getattr(sys, 'frozen', False):  # noqa: C901 # i
             )
             return self
 
-        def handleEvent_withReplyEvent_(self, event, replyEvent):  # noqa: N802 N803 # Required to override
+        def handleEvent_withReplyEvent_(self, event, replyEvent) -> None:  # noqa: N802 N803 # Required to override
             """Actual event handling from NSAppleEventManager."""
             protocolhandler.lasturl = urllib.parse.unquote(  # type: ignore # Its going to be a DPH in this code
                 event.paramDescriptorForKeyword_(keyDirectObject).stringValue()
@@ -229,18 +228,18 @@ elif sys.platform == 'win32' and getattr(sys, 'frozen', False) and not is_wine a
         https://en.wikipedia.org/wiki/Dynamic_Data_Exchange
         """
 
-        def __init__(self):
+        def __init__(self) -> None:
             super().__init__()
             self.thread: Optional[threading.Thread] = None
 
-        def start(self, master):
+        def start(self, master: 'tkinter.Tk') -> None:
             """Start the DDE thread."""
             super().start(master)
             self.thread = threading.Thread(target=self.worker, name='DDE worker')
             self.thread.daemon = True
             self.thread.start()
 
-        def close(self):
+        def close(self) -> None:
             """Stop the DDE thread."""
             thread = self.thread
             if thread:
@@ -248,7 +247,7 @@ elif sys.platform == 'win32' and getattr(sys, 'frozen', False) and not is_wine a
                 PostThreadMessageW(thread.ident, WM_QUIT, 0, 0)
                 thread.join()  # Wait for it to quit
 
-        def worker(self):
+        def worker(self) -> None:
             """Start a DDE server."""
             wndclass = WNDCLASS()
             wndclass.style = 0
@@ -320,21 +319,21 @@ else:  # Linux / Run from source
         This implementation uses a localhost HTTP server
         """
 
-        def __init__(self):
-            GenericProtocolHandler.__init__(self)
+        def __init__(self) -> None:
+            super().__init__()
             self.httpd = HTTPServer(('localhost', 0), HTTPRequestHandler)
             self.redirect = f'http://localhost:{self.httpd.server_port}/auth'
             logger.trace(f'Web server listening on {self.redirect}')
-            self.thread = None
+            self.thread: Optional[threading.Thread] = None
 
-        def start(self, master):
+        def start(self, master) -> None:
             """Start the HTTP server thread."""
             GenericProtocolHandler.start(self, master)
             self.thread = threading.Thread(target=self.worker, name='OAuth worker')
             self.thread.daemon = True
             self.thread.start()
 
-        def close(self):
+        def close(self) -> None:
             """Shutdown the HTTP server thread."""
             thread = self.thread
             if thread:
@@ -353,7 +352,7 @@ else:  # Linux / Run from source
 
             logger.debug('Done.')
 
-        def worker(self):
+        def worker(self) -> None:
             """HTTP Worker."""
             # TODO: This should probably be more ephemeral, and only handle one request, as its all we're expecting
             self.httpd.serve_forever()
@@ -361,7 +360,7 @@ else:  # Linux / Run from source
     class HTTPRequestHandler(BaseHTTPRequestHandler):
         """Simple HTTP server to handle IPC from protocol handler."""
 
-        def parse(self):
+        def parse(self) -> bool:
             """Parse a request."""
             url = urllib.parse.unquote(self.path)
             if url.startswith('/auth'):
@@ -373,12 +372,12 @@ else:  # Linux / Run from source
                 self.send_response(404)  # Not found
                 return False
 
-        def do_HEAD(self):  # noqa: N802 # Required to override
+        def do_HEAD(self) -> None:  # noqa: N802 # Required to override
             """Handle HEAD Request."""
             self.parse()
             self.end_headers()
 
-        def do_GET(self):  # noqa: N802 # Required to override
+        def do_GET(self) -> None:  # noqa: N802 # Required to override
             """Handle GET Request."""
             if self.parse():
                 self.send_header('Content-Type', 'text/html')