diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index 144f63a35443ded2a61603999896d549e242088f..e59849eebb5685b172500a5cf21e9756ae0ad521 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -86,10 +86,10 @@ repos:
   rev: v1.15.0
   hooks:
   - id: mypy
-    args: [kilter/service, tests]
+    args: [kilter/service, tests, --python-version=3.11]
     pass_filenames: false
     additional_dependencies:
-    - anyio ~=3.1
+    - anyio ~=4.0
     - kilter.protocol ~=0.6.0
     - sphinx
     - trio-typing
diff --git a/kilter/service/runner.py b/kilter/service/runner.py
index 0a89fce645f9e2776c9c3c706b28796da32d649b..99334c723fe457d9c300c96d823bf93aac9b22ee 100644
--- a/kilter/service/runner.py
+++ b/kilter/service/runner.py
@@ -405,6 +405,6 @@ class _TaskRunner:
 
 
 def _make_message_channel() -> tuple[MessageChannel, MessageChannel]:
-	lsend, rrecv = anyio.create_memory_object_stream(1, Message)  # type: ignore
-	rsend, lrecv = anyio.create_memory_object_stream(1, Message)  # type: ignore
+	lsend, rrecv = anyio.create_memory_object_stream[Message](1)
+	rsend, lrecv = anyio.create_memory_object_stream[Message](1)
 	return StapledObjectStream(lsend, lrecv), StapledObjectStream(rsend, rrecv)
diff --git a/pyproject.toml b/pyproject.toml
index 9d0474501a027447d585c5819a3bfaeb4bbf6d15..89737ef2404aa5a2458ffe6e7640f67c5e4c4002 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -11,9 +11,9 @@ license = {file = "LICENCE.txt"}
 readme = "README.md"
 dynamic = ["version", "description"]
 
-requires-python = "~=3.10"
+requires-python = "~=3.11"
 dependencies = [
-	"anyio ~=3.0",
+	"anyio ~=4.0",
 	"async-generator ~=1.2",
 	"kilter.protocol ~=0.6.0",
 	"typing-extensions ~=4.0",
@@ -27,7 +27,7 @@ classifiers = [
 
 [project.optional-dependencies]
 tests = [
-	"trio <0.22",  # Until anyio supports BaseExceptionGroup
+	"trio",
 ]
 docs = [
 	"sphinx ~=5.0",
diff --git a/tests/__init__.py b/tests/__init__.py
index 231d607463e5956f4e0c4c81b13c596b8ee9c3e0..99857bed0ca782ab1652bcbeb238f7770faa2336 100644
--- a/tests/__init__.py
+++ b/tests/__init__.py
@@ -2,22 +2,39 @@
 A package of tests for kilter.service modules
 """
 
+from __future__ import annotations
+
 import functools
 import os
 from collections.abc import Callable
 from collections.abc import Coroutine
+from collections.abc import Iterator
+from contextlib import contextmanager
 from inspect import iscoroutinefunction
+from typing import TYPE_CHECKING
 from typing import Any
+from typing import Protocol
+from typing import Self
+from typing import TypeVar
 from unittest import TestCase
 
 import trio
 
+E = TypeVar("E", bound=BaseException)
+
 SyncTest = Callable[[TestCase], None]
 AsyncTest = Callable[[TestCase], Coroutine[Any, Any, None]]
 
 LIMIT_SCALE_FACTOR = float(os.environ.get("LIMIT_SCALE_FACTOR", 1))
 
 
+if TYPE_CHECKING:
+	class AssertRaisesContext(Protocol[E]):  # noqa: D101
+		exception: E
+		expected: type[BaseException] | tuple[type[BaseException], ...]
+		msg: str|None
+
+
 class AsyncTestCase(TestCase):
 	"""
 	A variation of `unittest.TestCase` with support for awaitable (async) test functions
@@ -30,6 +47,28 @@ class AsyncTestCase(TestCase):
 			if name.startswith("test_") and iscoroutinefunction(value):
 				setattr(cls, name, _syncwrap(value, time_limit * LIMIT_SCALE_FACTOR))
 
+	@contextmanager
+	def assertRaises(  # type: ignore[override]
+		self,
+		expected_exception: type[E]|tuple[type[E], ...],
+		*,
+		msg: str|None = None,
+	) -> Iterator[AssertRaisesContext[E]]:
+		"""
+		Return a context manager that asserts a given exception is raised with the context
+
+		Extends the base assertRaises with support for ExceptionGroups.  If at most one leaf
+		exception is raised in the group and it matches the expected type, it will be
+		treated as a successful failure.
+		"""
+		with super().assertRaises(expected_exception, msg=msg) as context:
+			try:
+				yield context
+			except* expected_exception as grp:
+				exc = [*_leaf_exc(grp)]
+				assert len(exc) == 1
+				raise exc[0] from grp
+
 
 def _syncwrap(test: AsyncTest, time_limit: float) -> SyncTest:
 	@functools.wraps(test)
@@ -41,3 +80,11 @@ def _syncwrap(test: AsyncTest, time_limit: float) -> SyncTest:
 				raise TimeoutError
 		trio.run(limiter)
 	return wrap
+
+
+def _leaf_exc(group: BaseExceptionGroup) -> Iterator[BaseException]:
+	for exc in group.exceptions:
+		if isinstance(exc, BaseExceptionGroup):
+			yield from _leaf_exc(exc)
+		else:
+			yield exc
diff --git a/tests/mock_stream.py b/tests/mock_stream.py
index c2ccca59452fa765aa6a540a4549b9782ae13d25..05458997b7932178bdd185b2eecb5edf45a6b8ec 100644
--- a/tests/mock_stream.py
+++ b/tests/mock_stream.py
@@ -50,8 +50,8 @@ class MockMessageStream:
 		self.closed = False
 
 	async def __aenter__(self) -> Self:
-		send_obj, recv_bytes = anyio.create_memory_object_stream(5, bytes)
-		send_bytes, recv_obj = anyio.create_memory_object_stream(5, bytes)
+		send_obj, recv_bytes = anyio.create_memory_object_stream[bytes](5)
+		send_bytes, recv_obj = anyio.create_memory_object_stream[bytes](5)
 
 		self._stream = StapledObjectStream(send_obj, recv_obj)
 		self.peer_stream = StapledByteStream(