diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index 0b69df0..84082d0 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -3,7 +3,7 @@ ci:
 
 repos:
   - repo: https://github.com/astral-sh/ruff-pre-commit
-    rev: v0.7.4
+    rev: v0.9.1
     hooks:
       - id: ruff-format
         args: ["--diff", "src", "tests"]
diff --git a/poetry.lock b/poetry.lock
index f80a555..3742268 100644
--- a/poetry.lock
+++ b/poetry.lock
@@ -1825,30 +1825,30 @@ use-chardet-on-py3 = ["chardet (>=3.0.2,<6)"]
 
 [[package]]
 name = "ruff"
-version = "0.7.4"
+version = "0.9.1"
 description = "An extremely fast Python linter and code formatter, written in Rust."
 optional = true
 python-versions = ">=3.7"
 groups = ["main"]
 files = [
-    {file = "ruff-0.7.4-py3-none-linux_armv6l.whl", hash = "sha256:a4919925e7684a3f18e18243cd6bea7cfb8e968a6eaa8437971f681b7ec51478"},
-    {file = "ruff-0.7.4-py3-none-macosx_10_12_x86_64.whl", hash = "sha256:cfb365c135b830778dda8c04fb7d4280ed0b984e1aec27f574445231e20d6c63"},
-    {file = "ruff-0.7.4-py3-none-macosx_11_0_arm64.whl", hash = "sha256:63a569b36bc66fbadec5beaa539dd81e0527cb258b94e29e0531ce41bacc1f20"},
-    {file = "ruff-0.7.4-py3-none-manylinux_2_17_aarch64.manylinux2014_aarch64.whl", hash = "sha256:0d06218747d361d06fd2fdac734e7fa92df36df93035db3dc2ad7aa9852cb109"},
-    {file = "ruff-0.7.4-py3-none-manylinux_2_17_armv7l.manylinux2014_armv7l.whl", hash = "sha256:e0cea28d0944f74ebc33e9f934238f15c758841f9f5edd180b5315c203293452"},
-    {file = "ruff-0.7.4-py3-none-manylinux_2_17_i686.manylinux2014_i686.whl", hash = "sha256:80094ecd4793c68b2571b128f91754d60f692d64bc0d7272ec9197fdd09bf9ea"},
-    {file = "ruff-0.7.4-py3-none-manylinux_2_17_ppc64.manylinux2014_ppc64.whl", hash = "sha256:997512325c6620d1c4c2b15db49ef59543ef9cd0f4aa8065ec2ae5103cedc7e7"},
-    {file = "ruff-0.7.4-py3-none-manylinux_2_17_ppc64le.manylinux2014_ppc64le.whl", hash = "sha256:00b4cf3a6b5fad6d1a66e7574d78956bbd09abfd6c8a997798f01f5da3d46a05"},
-    {file = "ruff-0.7.4-py3-none-manylinux_2_17_s390x.manylinux2014_s390x.whl", hash = "sha256:7dbdc7d8274e1422722933d1edddfdc65b4336abf0b16dfcb9dedd6e6a517d06"},
-    {file = "ruff-0.7.4-py3-none-manylinux_2_17_x86_64.manylinux2014_x86_64.whl", hash = "sha256:0e92dfb5f00eaedb1501b2f906ccabfd67b2355bdf117fea9719fc99ac2145bc"},
-    {file = "ruff-0.7.4-py3-none-musllinux_1_2_aarch64.whl", hash = "sha256:3bd726099f277d735dc38900b6a8d6cf070f80828877941983a57bca1cd92172"},
-    {file = "ruff-0.7.4-py3-none-musllinux_1_2_armv7l.whl", hash = "sha256:2e32829c429dd081ee5ba39aef436603e5b22335c3d3fff013cd585806a6486a"},
-    {file = "ruff-0.7.4-py3-none-musllinux_1_2_i686.whl", hash = "sha256:662a63b4971807623f6f90c1fb664613f67cc182dc4d991471c23c541fee62dd"},
-    {file = "ruff-0.7.4-py3-none-musllinux_1_2_x86_64.whl", hash = "sha256:876f5e09eaae3eb76814c1d3b68879891d6fde4824c015d48e7a7da4cf066a3a"},
-    {file = "ruff-0.7.4-py3-none-win32.whl", hash = "sha256:75c53f54904be42dd52a548728a5b572344b50d9b2873d13a3f8c5e3b91f5cac"},
-    {file = "ruff-0.7.4-py3-none-win_amd64.whl", hash = "sha256:745775c7b39f914238ed1f1b0bebed0b9155a17cd8bc0b08d3c87e4703b990d6"},
-    {file = "ruff-0.7.4-py3-none-win_arm64.whl", hash = "sha256:11bff065102c3ae9d3ea4dc9ecdfe5a5171349cdd0787c1fc64761212fc9cf1f"},
-    {file = "ruff-0.7.4.tar.gz", hash = "sha256:cd12e35031f5af6b9b93715d8c4f40360070b2041f81273d0527683d5708fce2"},
+    {file = "ruff-0.9.1-py3-none-linux_armv6l.whl", hash = "sha256:84330dda7abcc270e6055551aca93fdde1b0685fc4fd358f26410f9349cf1743"},
+    {file = "ruff-0.9.1-py3-none-macosx_10_12_x86_64.whl", hash = "sha256:3cae39ba5d137054b0e5b472aee3b78a7c884e61591b100aeb544bcd1fc38d4f"},
+    {file = "ruff-0.9.1-py3-none-macosx_11_0_arm64.whl", hash = "sha256:50c647ff96f4ba288db0ad87048257753733763b409b2faf2ea78b45c8bb7fcb"},
+    {file = "ruff-0.9.1-py3-none-manylinux_2_17_aarch64.manylinux2014_aarch64.whl", hash = "sha256:f0c8b149e9c7353cace7d698e1656ffcf1e36e50f8ea3b5d5f7f87ff9986a7ca"},
+    {file = "ruff-0.9.1-py3-none-manylinux_2_17_armv7l.manylinux2014_armv7l.whl", hash = "sha256:beb3298604540c884d8b282fe7625651378e1986c25df51dec5b2f60cafc31ce"},
+    {file = "ruff-0.9.1-py3-none-manylinux_2_17_i686.manylinux2014_i686.whl", hash = "sha256:39d0174ccc45c439093971cc06ed3ac4dc545f5e8bdacf9f067adf879544d969"},
+    {file = "ruff-0.9.1-py3-none-manylinux_2_17_ppc64.manylinux2014_ppc64.whl", hash = "sha256:69572926c0f0c9912288915214ca9b2809525ea263603370b9e00bed2ba56dbd"},
+    {file = "ruff-0.9.1-py3-none-manylinux_2_17_ppc64le.manylinux2014_ppc64le.whl", hash = "sha256:937267afce0c9170d6d29f01fcd1f4378172dec6760a9f4dface48cdabf9610a"},
+    {file = "ruff-0.9.1-py3-none-manylinux_2_17_s390x.manylinux2014_s390x.whl", hash = "sha256:186c2313de946f2c22bdf5954b8dd083e124bcfb685732cfb0beae0c47233d9b"},
+    {file = "ruff-0.9.1-py3-none-manylinux_2_17_x86_64.manylinux2014_x86_64.whl", hash = "sha256:3f94942a3bb767675d9a051867c036655fe9f6c8a491539156a6f7e6b5f31831"},
+    {file = "ruff-0.9.1-py3-none-musllinux_1_2_aarch64.whl", hash = "sha256:728d791b769cc28c05f12c280f99e8896932e9833fef1dd8756a6af2261fd1ab"},
+    {file = "ruff-0.9.1-py3-none-musllinux_1_2_armv7l.whl", hash = "sha256:2f312c86fb40c5c02b44a29a750ee3b21002bd813b5233facdaf63a51d9a85e1"},
+    {file = "ruff-0.9.1-py3-none-musllinux_1_2_i686.whl", hash = "sha256:ae017c3a29bee341ba584f3823f805abbe5fe9cd97f87ed07ecbf533c4c88366"},
+    {file = "ruff-0.9.1-py3-none-musllinux_1_2_x86_64.whl", hash = "sha256:5dc40a378a0e21b4cfe2b8a0f1812a6572fc7b230ef12cd9fac9161aa91d807f"},
+    {file = "ruff-0.9.1-py3-none-win32.whl", hash = "sha256:46ebf5cc106cf7e7378ca3c28ce4293b61b449cd121b98699be727d40b79ba72"},
+    {file = "ruff-0.9.1-py3-none-win_amd64.whl", hash = "sha256:342a824b46ddbcdddd3abfbb332fa7fcaac5488bf18073e841236aadf4ad5c19"},
+    {file = "ruff-0.9.1-py3-none-win_arm64.whl", hash = "sha256:1cd76c7f9c679e6e8f2af8f778367dca82b95009bc7b1a85a47f1521ae524fa7"},
+    {file = "ruff-0.9.1.tar.gz", hash = "sha256:fd2b25ecaf907d6458fa842675382c8597b3c746a2dde6717fe3415425df0c17"},
 ]
 
 [[package]]
@@ -2256,4 +2256,4 @@ rust-codec = ["betterproto-rust-codec"]
 [metadata]
 lock-version = "2.1"
 python-versions = ">=3.9,<4.0"
-content-hash = "8803a27b9a438cf868b4881dc73e77bd8dddb88cae665ab6a90a9cc063ad4150"
+content-hash = "cf90b82485ce6837f190477b98778fedc112e9efb6b0dde487da9d65cd92db3b"
diff --git a/pyproject.toml b/pyproject.toml
index b50af77..7b1b6e7 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -17,7 +17,7 @@ dynamic = ["dependencies"]
 
 [tool.poetry.dependencies]
 # The Ruff version is pinned. To update it, also update it in .pre-commit-config.yaml
-ruff = { version = "~0.7.4", optional = true }
+ruff = { version = "~0.9.1", optional = true }
 grpclib = "^0.4.1"
 jinja2 = { version = ">=3.0.3", optional = true }
 python-dateutil = "^2.8"
diff --git a/src/betterproto/__init__.py b/src/betterproto/__init__.py
index 7ed3785..ce8a26a 100644
--- a/src/betterproto/__init__.py
+++ b/src/betterproto/__init__.py
@@ -2011,10 +2011,10 @@ class _Timestamp(Timestamp):
             return f"{result}Z"
         if (nanos % 1e6) == 0:
             # Serialize 3 fractional digits.
-            return f"{result}.{int(nanos // 1e6) :03d}Z"
+            return f"{result}.{int(nanos // 1e6):03d}Z"
         if (nanos % 1e3) == 0:
             # Serialize 6 fractional digits.
-            return f"{result}.{int(nanos // 1e3) :06d}Z"
+            return f"{result}.{int(nanos // 1e3):06d}Z"
         # Serialize 9 fractional digits.
         return f"{result}.{nanos:09d}"
 
diff --git a/tests/grpc/test_grpclib_client.py b/tests/grpc/test_grpclib_client.py
index f64351c..b9eb559 100644
--- a/tests/grpc/test_grpclib_client.py
+++ b/tests/grpc/test_grpclib_client.py
@@ -26,12 +26,12 @@ async def _test_client(client: ThingServiceClient, name="clean room", **kwargs):
 
 def _assert_request_meta_received(deadline, metadata):
     def server_side_test(stream):
-        assert stream.deadline._timestamp == pytest.approx(
-            deadline._timestamp, 1
-        ), "The provided deadline should be received serverside"
-        assert (
-            stream.metadata["authorization"] == metadata["authorization"]
-        ), "The provided authorization metadata should be received serverside"
+        assert stream.deadline._timestamp == pytest.approx(deadline._timestamp, 1), (
+            "The provided deadline should be received serverside"
+        )
+        assert stream.metadata["authorization"] == metadata["authorization"], (
+            "The provided authorization metadata should be received serverside"
+        )
 
     return server_side_test
 
@@ -265,9 +265,9 @@ async def test_async_gen_for_stream_stream_request():
             else:
                 # No more things to send make sure channel is closed
                 request_chan.close()
-        assert response_index == len(
-            expected_things
-        ), "Didn't receive all expected responses"
+        assert response_index == len(expected_things), (
+            "Didn't receive all expected responses"
+        )
 
 
 @pytest.mark.asyncio
diff --git a/tests/inputs/casing/test_casing.py b/tests/inputs/casing/test_casing.py
index 9ca4243..b050043 100644
--- a/tests/inputs/casing/test_casing.py
+++ b/tests/inputs/casing/test_casing.py
@@ -4,20 +4,20 @@ from tests.output_betterproto.casing import Test
 
 def test_message_attributes():
     message = Test()
-    assert hasattr(
-        message, "snake_case_message"
-    ), "snake_case field name is same in python"
+    assert hasattr(message, "snake_case_message"), (
+        "snake_case field name is same in python"
+    )
     assert hasattr(message, "camel_case"), "CamelCase field is snake_case in python"
     assert hasattr(message, "uppercase"), "UPPERCASE field is lowercase in python"
 
 
 def test_message_casing():
-    assert hasattr(
-        casing, "SnakeCaseMessage"
-    ), "snake_case Message name is converted to CamelCase in python"
+    assert hasattr(casing, "SnakeCaseMessage"), (
+        "snake_case Message name is converted to CamelCase in python"
+    )
 
 
 def test_enum_casing():
-    assert hasattr(
-        casing, "MyEnum"
-    ), "snake_case Enum name is converted to CamelCase in python"
+    assert hasattr(casing, "MyEnum"), (
+        "snake_case Enum name is converted to CamelCase in python"
+    )
diff --git a/tests/inputs/casing_inner_class/test_casing_inner_class.py b/tests/inputs/casing_inner_class/test_casing_inner_class.py
index 267b105..466b532 100644
--- a/tests/inputs/casing_inner_class/test_casing_inner_class.py
+++ b/tests/inputs/casing_inner_class/test_casing_inner_class.py
@@ -2,13 +2,13 @@ import tests.output_betterproto.casing_inner_class as casing_inner_class
 
 
 def test_message_casing_inner_class_name():
-    assert hasattr(
-        casing_inner_class, "TestInnerClass"
-    ), "Inline defined Message is correctly converted to CamelCase"
+    assert hasattr(casing_inner_class, "TestInnerClass"), (
+        "Inline defined Message is correctly converted to CamelCase"
+    )
 
 
 def test_message_casing_inner_class_attributes():
     message = casing_inner_class.Test()
-    assert hasattr(
-        message.inner, "old_exp"
-    ), "Inline defined Message attribute is snake_case"
+    assert hasattr(message.inner, "old_exp"), (
+        "Inline defined Message attribute is snake_case"
+    )
diff --git a/tests/inputs/casing_message_field_uppercase/casing_message_field_uppercase.py b/tests/inputs/casing_message_field_uppercase/casing_message_field_uppercase.py
index 2b32b53..c1a973c 100644
--- a/tests/inputs/casing_message_field_uppercase/casing_message_field_uppercase.py
+++ b/tests/inputs/casing_message_field_uppercase/casing_message_field_uppercase.py
@@ -3,12 +3,12 @@ from tests.output_betterproto.casing_message_field_uppercase import Test
 
 def test_message_casing():
     message = Test()
-    assert hasattr(
-        message, "uppercase"
-    ), "UPPERCASE attribute is converted to 'uppercase' in python"
-    assert hasattr(
-        message, "uppercase_v2"
-    ), "UPPERCASE_V2 attribute is converted to 'uppercase_v2' in python"
-    assert hasattr(
-        message, "upper_camel_case"
-    ), "UPPER_CAMEL_CASE attribute is converted to upper_camel_case in python"
+    assert hasattr(message, "uppercase"), (
+        "UPPERCASE attribute is converted to 'uppercase' in python"
+    )
+    assert hasattr(message, "uppercase_v2"), (
+        "UPPERCASE_V2 attribute is converted to 'uppercase_v2' in python"
+    )
+    assert hasattr(message, "upper_camel_case"), (
+        "UPPER_CAMEL_CASE attribute is converted to upper_camel_case in python"
+    )
diff --git a/tests/inputs/enum/test_enum.py b/tests/inputs/enum/test_enum.py
index 21a5ac3..0663bea 100644
--- a/tests/inputs/enum/test_enum.py
+++ b/tests/inputs/enum/test_enum.py
@@ -27,9 +27,9 @@ def test_enum_is_comparable_with_int():
 
 
 def test_enum_to_dict():
-    assert (
-        "choice" not in Test(choice=Choice.ZERO).to_dict()
-    ), "Default enum value is not serialized"
+    assert "choice" not in Test(choice=Choice.ZERO).to_dict(), (
+        "Default enum value is not serialized"
+    )
     assert (
         Test(choice=Choice.ZERO).to_dict(include_default_values=True)["choice"]
         == "ZERO"
diff --git a/tests/test_get_ref_type.py b/tests/test_get_ref_type.py
index 7b529bd..2179662 100644
--- a/tests/test_get_ref_type.py
+++ b/tests/test_get_ref_type.py
@@ -56,9 +56,9 @@ def test_reference_google_wellknown_types_non_wrappers(
     )
 
     assert name == expected_name
-    assert imports.__contains__(
-        expected_import
-    ), f"{expected_import} not found in {imports}"
+    assert imports.__contains__(expected_import), (
+        f"{expected_import} not found in {imports}"
+    )
 
 
 @pytest.mark.parametrize(
@@ -102,9 +102,9 @@ def test_reference_google_wellknown_types_non_wrappers_pydantic(
     )
 
     assert name == expected_name
-    assert imports.__contains__(
-        expected_import
-    ), f"{expected_import} not found in {imports}"
+    assert imports.__contains__(expected_import), (
+        f"{expected_import} not found in {imports}"
+    )
 
 
 @pytest.mark.parametrize(
diff --git a/tests/test_version.py b/tests/test_version.py
index 0a6ca6c..09bc115 100644
--- a/tests/test_version.py
+++ b/tests/test_version.py
@@ -11,6 +11,6 @@ PROJECT_TOML = Path(__file__).joinpath("..", "..", "pyproject.toml").resolve()
 def test_version():
     with PROJECT_TOML.open() as toml_file:
         project_config = tomlkit.loads(toml_file.read())
-    assert (
-        __version__ == project_config["project"]["version"]
-    ), "Project version should match in package and package config"
+    assert __version__ == project_config["project"]["version"], (
+        "Project version should match in package and package config"
+    )