diff --git a/prospector/postfilter.py b/prospector/postfilter.py
index 72c893aa..51d5a0cb 100644
--- a/prospector/postfilter.py
+++ b/prospector/postfilter.py
@@ -1,11 +1,10 @@
 from pathlib import Path
-from typing import List
 
 from prospector.message import Message
 from prospector.suppression import get_suppressions
 
 
-def filter_messages(filepaths: List[Path], messages: List[Message]) -> List[Message]:
+def filter_messages(filepaths: list[Path], messages: list[Message]) -> list[Message]:
     """
     This method post-processes all messages output by all tools, in order to filter
     out any based on the overall output.
diff --git a/prospector/tools/pylint/collector.py b/prospector/tools/pylint/collector.py
index be49713b..1002bc10 100644
--- a/prospector/tools/pylint/collector.py
+++ b/prospector/tools/pylint/collector.py
@@ -1,5 +1,4 @@
 from io import StringIO
-from typing import List
 
 from pylint.exceptions import UnknownMessageError
 from pylint.message import Message as PylintMessage
@@ -35,5 +34,5 @@ def handle_message(self, msg: PylintMessage) -> None:
         message = Message("pylint", msg_symbol, loc, msg.msg)
         self._messages.append(message)
 
-    def get_messages(self) -> List[Message]:
+    def get_messages(self) -> list[Message]:
         return self._messages
diff --git a/pyproject.toml b/pyproject.toml
index 4cddc5be..b4aa31f4 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -88,6 +88,7 @@ build-backend = "poetry.core.masonry.api"
 
 [tool.ruff]
 line-length = 120
+target-version = "py39"
 
 [tool.ruff.lint]
 fixable = ["ALL"]
diff --git a/tests/utils.py b/tests/utils.py
index b21471fa..38217cb0 100644
--- a/tests/utils.py
+++ b/tests/utils.py
@@ -22,8 +22,10 @@ def patch_cwd(set_cwd: Path):
     # for this test to work in all python versions prospector supports, both need to
     # be patched (or, an "if python version" statement but it's easier to just patch both)
     cwd_str = str(set_cwd.absolute())
-    with patch("pathlib.Path.cwd", new=lambda: set_cwd), patch("os.getcwd", new=lambda: cwd_str), patch(
-        "os.curdir", new=cwd_str
+    with (
+        patch("pathlib.Path.cwd", new=lambda: set_cwd),
+        patch("os.getcwd", new=lambda: cwd_str),
+        patch("os.curdir", new=cwd_str),
     ):
         # Turns out that Python 3.10 added the `getcwd` to the _NormalAccessor instead of falling
         # back on os.getcwd, and so this needs to be patched too...