diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index 34237922..04e0869f 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -17,7 +17,7 @@ repos:
   - id: check-yaml
 
 - repo: https://github.com/astral-sh/ruff-pre-commit
-  rev: v0.15.9
+  rev: v0.17.4
   hooks:
     - id: ruff
       args: [--fix, --exit-non-zero-on-fix, --show-fixes]
@@ -32,7 +32,7 @@ repos:
 
 # Type checking
 - repo: https://github.com/pre-commit/mirrors-mypy
-  rev: v1.20.0
+  rev: v2.4.1
   hooks:
   - id: mypy
     files: 'src/.*\.py$'
diff --git a/README.rst b/README.rst
index ed71f7db..55f58bd4 100644
--- a/README.rst
+++ b/README.rst
@@ -39,4 +39,4 @@ To achieve more complex workflows services can be interconnected using
 `recipes`_ whereby the output of one service can be directed
 onwards to other services.
 
-.. _recipes: https://github.com/DiamondLightSource/python-workflows/tree/main/src/workflows/recipe/README.MD
+.. _recipes: https://github.com/DiamondLightSource/python-workflows/tree/main/src/workflows/recipe/README.md
diff --git a/src/workflows/recipe/README.MD b/src/workflows/recipe/README.md
similarity index 97%
rename from src/workflows/recipe/README.MD
rename to src/workflows/recipe/README.md
index e26b7692..2e026bb8 100644
--- a/src/workflows/recipe/README.MD
+++ b/src/workflows/recipe/README.md
@@ -1,6 +1,6 @@
 ## Recipes
 
-A [service](../services/README.MD) listens on a [channel](../transport/README.MD), acts on incoming messages, and produces some output.
+A [service](../services/README.md) listens on a [channel](../transport/README.md), acts on incoming messages, and produces some output.
 The place where this output is sent to could be hardcoded, ie. written into the source code of the service.
 This makes the service structure rigid, and connecting one service to the output of another requires coordinating the source code of both services.
 Naturally, this approach does not scale well.
diff --git a/src/workflows/services/README.MD b/src/workflows/services/README.md
similarity index 100%
rename from src/workflows/services/README.MD
rename to src/workflows/services/README.md
diff --git a/src/workflows/transport/common_transport.py b/src/workflows/transport/common_transport.py
index 551af0a7..f133aead 100644
--- a/src/workflows/transport/common_transport.py
+++ b/src/workflows/transport/common_transport.py
@@ -24,7 +24,7 @@ class CommonTransport:
     Contains e.g. the logic to manage subscriptions and transactions.
     """
 
-    __callback_interceptor = None
+    __callback_interceptor: Callable[[MessageCallback], MessageCallback] | None = None
     __subscriptions: dict[int, dict[str, Any]] = {}
     __subscription_id: int = 0
     __transactions: set[int] = set()