diff --git a/pyproject.toml b/pyproject.toml
index b93cb99a..9d37d3ed 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -84,3 +84,5 @@ namespaces = false
 [tool.ruff]
 line-length = 99
 exclude = ['tests/assets'] # These are sample packages for tests to run under - we don't want ruff to mess with them.
+[tool.ruff.lint]
+select = ["E4", "E7", "E9", "F", "UP"]
diff --git a/src/grimp/adaptors/caching.py b/src/grimp/adaptors/caching.py
index 36310272..d6a10af4 100644
--- a/src/grimp/adaptors/caching.py
+++ b/src/grimp/adaptors/caching.py
@@ -2,7 +2,6 @@
 
 import json
 import logging
-from typing import Optional
 
 from grimp.application.ports.filesystem import BasicFileSystem
 from grimp.application.ports.modulefinder import FoundPackage, ModuleFile
@@ -13,7 +12,7 @@
 from grimp import _rustgrimp as rust  # type: ignore[attr-defined]
 
 logger = logging.getLogger(__name__)
-PrimitiveFormat = dict[str, list[tuple[str, Optional[int], str]]]
+PrimitiveFormat = dict[str, list[tuple[str, int | None, str]]]
 
 
 class CacheFileNamer: