diff --git a/plugins/b64.py b/plugins/b64.py
index d56ac5b3..1fec6123 100644
--- a/plugins/b64.py
+++ b/plugins/b64.py
@@ -24,7 +24,9 @@ This plugin also respects security guidelines listed in XEP-0419.
 
 from base64 import b64decode, b64encode
 from poezio.plugin_e2ee import E2EEPlugin
-from slixmpp import Message
+from poezio.tabs import ChatTab
+from slixmpp import Message, JID
+from typing import Optional
 
 
 class Plugin(E2EEPlugin):
@@ -37,14 +39,14 @@ class Plugin(E2EEPlugin):
     # This encryption mechanism is using <body/> as a container
     replace_body_with_eme = False
 
-    def decrypt(self, message: Message, _tab) -> None:
+    async def decrypt(self, message: Message, jid: Optional[JID], _tab: ChatTab) -> None:
         """
             Decrypt base64
         """
         body = message['body']
         message['body'] = b64decode(body.encode()).decode()
 
-    def encrypt(self, message: Message, _tab) -> None:
+    async def encrypt(self, message: Message, jid: Optional[JID], _tab: ChatTab) -> None:
         """
             Encrypt to base64
         """
diff --git a/plugins/emoji_ascii.py b/plugins/emoji_ascii.py
index 6629c50e..4beec3b1 100644
--- a/plugins/emoji_ascii.py
+++ b/plugins/emoji_ascii.py
@@ -21,10 +21,12 @@ import os
 import re
 
 from poezio.plugin import BasePlugin
+from typing import Dict
+
 
 class Plugin(BasePlugin):
-    emoji_to_ascii = {}
-    ascii_to_emoji = {}
+    emoji_to_ascii: Dict[str, str] = {}
+    ascii_to_emoji: Dict[str, str] = {}
     emoji_pattern = None
     alias_pattern = None
 
diff --git a/plugins/qr.py b/plugins/qr.py
index 25530248..9b05750d 100755
--- a/plugins/qr.py
+++ b/plugins/qr.py
@@ -3,7 +3,8 @@
 import io
 import logging
 import qrcode
-import sys
+
+from typing import Dict, Callable
 
 from poezio import windows
 from poezio.tabs import Tab
diff --git a/plugins/screen_detach.py b/plugins/screen_detach.py
index 0a2514c4..1f908513 100644
--- a/plugins/screen_detach.py
+++ b/plugins/screen_detach.py
@@ -43,10 +43,10 @@ DEFAULT_CONFIG = {
 # overload if this is not how your stuff
 # is configured
 try:
-    LOGIN = os.getlogin()
+    LOGIN = os.getlogin() or ''
     LOGIN_TMUX = os.getuid()
 except Exception:
-    LOGIN = os.getenv('USER')
+    LOGIN = os.getenv('USER') or ''
     LOGIN_TMUX = os.getuid()
 
 SCREEN_DIR = '/var/run/screens/S-%s' % LOGIN
diff --git a/plugins/untrackme.py b/plugins/untrackme.py
index c5db1a9d..ceddc5c5 100644
--- a/plugins/untrackme.py
+++ b/plugins/untrackme.py
@@ -49,7 +49,7 @@ def proxy(service: str) -> Callable[[str], str]:
 class Plugin(BasePlugin):
     """UntrackMe"""
 
-    default_config: Dict[str, str] = {
+    default_config: Dict[str, Dict[str, Union[str, bool]]] = {
         'default': {
             'cleanup': True,
             'redirect': True,
diff --git a/plugins/user_extras.py b/plugins/user_extras.py
index b66545ed..ad49a142 100644
--- a/plugins/user_extras.py
+++ b/plugins/user_extras.py
@@ -369,6 +369,8 @@ class Plugin(BasePlugin):
                 return
             if activity[0]:
                 general = ACTIVITIES.get(activity[0])
+                if general is None:
+                    return
                 s = general['category']
                 if activity[1]:
                     s = s + '/' + general.get(activity[1], 'other')
diff --git a/poezio/plugin.py b/poezio/plugin.py
index 0ba13412..5fde7a12 100644
--- a/poezio/plugin.py
+++ b/poezio/plugin.py
@@ -4,7 +4,7 @@ These are used in the plugin system added in poezio 0.7.5
 (see plugin_manager.py)
 """
 
-from typing import Any, Dict, Set
+from typing import Any, Dict, Set, Optional
 from asyncio import iscoroutinefunction
 from functools import partial
 from configparser import RawConfigParser
@@ -404,7 +404,7 @@ class BasePlugin(object, metaclass=SafetyMetaclass):
     # Internal use only
     _unloading = False
 
-    default_config = None
+    default_config: Optional[Dict[Any, Any]] = None
     dependencies: Set[str] = set()
     # This dict will get populated when the plugin is initialized
     refs: Dict[str, Any] = {}