diff --git a/tildes/requirements.txt b/tildes/requirements.txt
index 8a871f2..a451995 100644
--- a/tildes/requirements.txt
+++ b/tildes/requirements.txt
@@ -34,7 +34,7 @@ MarkupSafe==1.1.1
 marshmallow==2.20.5
 mccabe==0.6.1
 more-itertools==7.2.0
-mypy==0.730
+mypy==0.740
 mypy-extensions==0.4.2
 packaging==19.2
 parso==0.5.1
diff --git a/tildes/tildes/lib/url_transform.py b/tildes/tildes/lib/url_transform.py
index 6f1c7fe..85b449f 100644
--- a/tildes/tildes/lib/url_transform.py
+++ b/tildes/tildes/lib/url_transform.py
@@ -196,11 +196,15 @@ class WikipediaMobileConverter(UrlTransformer):
     @classmethod
     def is_applicable(cls, parsed_url: ParseResult) -> bool:
         """Return whether this transformation should be applied to the url."""
+        assert parsed_url.hostname is not None  # mypy workaround
+
         return parsed_url.hostname.endswith(".m.wikipedia.org") and has_path(parsed_url)
 
     @classmethod
     def apply_transformation(cls, parsed_url: ParseResult) -> ParseResult:
         """Apply the actual transformation process to the url."""
+        assert parsed_url.hostname is not None  # mypy workaround
+
         new_domain = parsed_url.hostname.replace(".m.wikipedia.org", ".wikipedia.org")
         return parsed_url._replace(netloc=new_domain)
 
diff --git a/tildes/tildes/models/message/message.py b/tildes/tildes/models/message/message.py
index 5df1109..6a48ff5 100644
--- a/tildes/tildes/models/message/message.py
+++ b/tildes/tildes/models/message/message.py
@@ -193,7 +193,7 @@ class MessageConversation(DatabaseModel):
             raise ValueError("User is not a participant in this conversation.")
 
         user_id = user.user_id
-        self.unread_user_ids = (  # type: ignore
+        self.unread_user_ids = (
             MessageConversation.unread_user_ids - user_id  # type: ignore
         )
 
diff --git a/tildes/tildes/models/topic/topic.py b/tildes/tildes/models/topic/topic.py
index fd06e46..ed0c3e8 100644
--- a/tildes/tildes/models/topic/topic.py
+++ b/tildes/tildes/models/topic/topic.py
@@ -420,8 +420,8 @@ class Topic(DatabaseModel):
             return TopicContentType.TEXT
 
         if self.is_link_type:
-            parsed_url = urlparse(self.link)  # type: ignore
-            url_path = PurePosixPath(parsed_url.path)
+            parsed_url = urlparse(self.link)
+            url_path = PurePosixPath(str(parsed_url.path))
 
             if url_path.suffix.lower() == ".pdf":
                 return TopicContentType.PDF