diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 96e0cb1..3a4908c 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -18,7 +18,6 @@ jobs:
     strategy:
       matrix:
         python:
-          - "3.9"
           - "3.10"
           - "3.11"
           - "3.12"
diff --git a/CHANGELOG.md b/CHANGELOG.md
index e03d0c9..18fb4aa 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -11,7 +11,7 @@ adheres to [Semantic Versioning](https://semver.org/).
 
 ### :boom: Breaking changes
 
-- End of Python 3.7 and 3.8 support
+- End of Python 3.7, 3.8, and 3.9 support
 
 ### :house: Internal
 
diff --git a/pyproject.toml b/pyproject.toml
index 943c83c..f56c53c 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -13,7 +13,6 @@ classifiers = [
     "Programming Language :: Python",
     "Programming Language :: Python :: 3",
     "Programming Language :: Python :: 3 :: Only",
-    "Programming Language :: Python :: 3.9",
     "Programming Language :: Python :: 3.10",
     "Programming Language :: Python :: 3.11",
     "Programming Language :: Python :: 3.12",
@@ -23,7 +22,7 @@ classifiers = [
     "Topic :: System :: Archiving",
     "Topic :: System :: Archiving :: Compression",
 ]
-requires-python = ">=3.9"
+requires-python = ">=3.10"
 
 [project.urls]
 Homepage = "https://github.com/rogdham/python-xz"
@@ -139,7 +138,7 @@ testpaths = ["tests"]
 
 [tool.ruff]
 src = ["src"]
-target-version = "py39"
+target-version = "py310"
 
 [tool.ruff.lint]
 select = ["ALL"]
diff --git a/src/xz/block.py b/src/xz/block.py
index 6b4a00a..9f31a8b 100644
--- a/src/xz/block.py
+++ b/src/xz/block.py
@@ -1,6 +1,5 @@
 from io import DEFAULT_BUFFER_SIZE, SEEK_SET
 from lzma import FORMAT_XZ, LZMACompressor, LZMADecompressor, LZMAError
-from typing import Optional, Union
 
 from xz.common import (
     XZError,
@@ -122,7 +121,7 @@ def __init__(
         uncompressed_size: int,
         preset: _LZMAPresetType = None,
         filters: _LZMAFiltersType = None,
-        block_read_strategy: Optional[_BlockReadStrategyType] = None,
+        block_read_strategy: _BlockReadStrategyType | None = None,
     ) -> None:
         super().__init__(uncompressed_size)
         self.fileobj = fileobj
@@ -131,7 +130,7 @@ def __init__(
         self.filters = filters
         self.block_read_strategy = block_read_strategy or KeepBlockReadStrategy()
         self.unpadded_size = unpadded_size
-        self.operation: Union[BlockRead, BlockWrite, None] = None
+        self.operation: BlockRead | BlockWrite | None = None
 
     @property
     def uncompressed_size(self) -> int:
diff --git a/src/xz/file.py b/src/xz/file.py
index e81ccb3..7d96993 100644
--- a/src/xz/file.py
+++ b/src/xz/file.py
@@ -1,7 +1,6 @@
 from io import SEEK_CUR, SEEK_END
 import os
-import sys
-from typing import BinaryIO, Optional, cast
+from typing import BinaryIO, cast
 import warnings
 
 from xz.common import DEFAULT_CHECK, XZError
@@ -36,7 +35,7 @@ def __init__(
         check: int = -1,
         preset: _LZMAPresetType = None,
         filters: _LZMAFiltersType = None,
-        block_read_strategy: Optional[_BlockReadStrategyType] = None,
+        block_read_strategy: _BlockReadStrategyType | None = None,
     ) -> None:
         """Open an XZ file in binary mode.
 
@@ -113,7 +112,7 @@ def __init__(
         self._close_check_empty = self._mode[0] != "r"
 
     @property
-    def _last_stream(self) -> Optional[XZStream]:
+    def _last_stream(self) -> XZStream | None:
         try:
             return self._fileobjs.last_item
         except KeyError:
@@ -145,10 +144,9 @@ def close(self) -> None:
         finally:
             if self._close_fileobj:
                 self.fileobj.close()  # self.fileobj exists at this point
-            if sys.version_info < (3, 10):  # pragma: no cover
-                # fix coverage issue on some Python versions
-                # see https://github.com/nedbat/coveragepy/issues/1480
-                pass
+
+            # fix coverage issue on some Python versions
+            pass  # noqa: PIE790
 
     @property
     def stream_boundaries(self) -> list[int]:
diff --git a/src/xz/io.py b/src/xz/io.py
index 8dcd1fc..b03074f 100644
--- a/src/xz/io.py
+++ b/src/xz/io.py
@@ -6,7 +6,7 @@
     IOBase,
     UnsupportedOperation,
 )
-from typing import BinaryIO, Generic, Optional, TypeVar, Union, cast
+from typing import BinaryIO, Generic, TypeVar, cast
 
 from xz.utils import FloorDict
 
@@ -150,7 +150,7 @@ def write(self, data: bytes) -> int:
             self._length = max(self._length, self._pos)
         return written_bytes
 
-    def truncate(self, size: Optional[int] = None) -> int:
+    def truncate(self, size: int | None = None) -> int:
         """Truncate file to size bytes.
         Size defaults to the current IO position as reported by tell().
 
@@ -242,7 +242,7 @@ def _read(self, size: int) -> bytes:
 class IOProxy(IOAbstract):
     def __init__(
         self,
-        fileobj: Union[BinaryIO, IOBase],  # see typing note on top of this file
+        fileobj: BinaryIO | IOBase,  # see typing note on top of this file
         start: int,
         end: int,
     ) -> None:
@@ -290,7 +290,7 @@ def _write_after(self) -> None:
 
     def _write(self, data: bytes) -> int:
         if self._fileobjs:
-            fileobj: Optional[T] = self._get_fileobj()
+            fileobj: T | None = self._get_fileobj()
         else:
             fileobj = None
 
diff --git a/src/xz/open.py b/src/xz/open.py
index 1608a14..b16b0f8 100644
--- a/src/xz/open.py
+++ b/src/xz/open.py
@@ -1,5 +1,5 @@
 from io import TextIOWrapper
-from typing import BinaryIO, Optional, Union, cast, overload
+from typing import BinaryIO, cast, overload
 
 from xz.file import XZFile
 from xz.typing import (
@@ -22,10 +22,10 @@ def __init__(
         check: int = -1,
         preset: _LZMAPresetType = None,
         filters: _LZMAFiltersType = None,
-        block_read_strategy: Optional[_BlockReadStrategyType] = None,
-        encoding: Optional[str] = None,
-        errors: Optional[str] = None,
-        newline: Optional[str] = None,
+        block_read_strategy: _BlockReadStrategyType | None = None,
+        encoding: str | None = None,
+        errors: str | None = None,
+        newline: str | None = None,
     ) -> None:
         self.xz_file = XZFile(
             filename,
@@ -75,11 +75,11 @@ def xz_open(
     check: int = -1,
     preset: _LZMAPresetType = None,
     filters: _LZMAFiltersType = None,
-    block_read_strategy: Optional[_BlockReadStrategyType] = None,
+    block_read_strategy: _BlockReadStrategyType | None = None,
     # text-mode kwargs
-    encoding: Optional[str] = None,
-    errors: Optional[str] = None,
-    newline: Optional[str] = None,
+    encoding: str | None = None,
+    errors: str | None = None,
+    newline: str | None = None,
 ) -> XZFile: ...
 
 
@@ -92,11 +92,11 @@ def xz_open(
     check: int = -1,
     preset: _LZMAPresetType = None,
     filters: _LZMAFiltersType = None,
-    block_read_strategy: Optional[_BlockReadStrategyType] = None,
+    block_read_strategy: _BlockReadStrategyType | None = None,
     # text-mode kwargs
-    encoding: Optional[str] = None,
-    errors: Optional[str] = None,
-    newline: Optional[str] = None,
+    encoding: str | None = None,
+    errors: str | None = None,
+    newline: str | None = None,
 ) -> _XZFileText: ...
 
 
@@ -109,12 +109,12 @@ def xz_open(
     check: int = -1,
     preset: _LZMAPresetType = None,
     filters: _LZMAFiltersType = None,
-    block_read_strategy: Optional[_BlockReadStrategyType] = None,
+    block_read_strategy: _BlockReadStrategyType | None = None,
     # text-mode kwargs
-    encoding: Optional[str] = None,
-    errors: Optional[str] = None,
-    newline: Optional[str] = None,
-) -> Union[XZFile, _XZFileText]: ...
+    encoding: str | None = None,
+    errors: str | None = None,
+    newline: str | None = None,
+) -> XZFile | _XZFileText: ...
 
 
 def xz_open(
@@ -125,12 +125,12 @@ def xz_open(
     check: int = -1,
     preset: _LZMAPresetType = None,
     filters: _LZMAFiltersType = None,
-    block_read_strategy: Optional[_BlockReadStrategyType] = None,
+    block_read_strategy: _BlockReadStrategyType | None = None,
     # text-mode kwargs
-    encoding: Optional[str] = None,
-    errors: Optional[str] = None,
-    newline: Optional[str] = None,
-) -> Union[XZFile, _XZFileText]:
+    encoding: str | None = None,
+    errors: str | None = None,
+    newline: str | None = None,
+) -> XZFile | _XZFileText:
     """Open an XZ file in binary or text mode.
 
     filename can be either an actual file name (given as a str, bytes,
diff --git a/src/xz/stream.py b/src/xz/stream.py
index 49992b8..10f2797 100644
--- a/src/xz/stream.py
+++ b/src/xz/stream.py
@@ -1,5 +1,5 @@
 from io import SEEK_CUR
-from typing import BinaryIO, Optional
+from typing import BinaryIO
 
 from xz.block import XZBlock
 from xz.common import (
@@ -22,7 +22,7 @@ def __init__(
         check: int,
         preset: _LZMAPresetType = None,
         filters: _LZMAFiltersType = None,
-        block_read_strategy: Optional[_BlockReadStrategyType] = None,
+        block_read_strategy: _BlockReadStrategyType | None = None,
     ) -> None:
         super().__init__()
         self.fileobj = fileobj
@@ -49,7 +49,7 @@ def _fileobj_blocks_end_pos(self) -> int:
     def parse(
         cls,
         fileobj: BinaryIO,
-        block_read_strategy: Optional[_BlockReadStrategyType] = None,
+        block_read_strategy: _BlockReadStrategyType | None = None,
     ) -> "XZStream":
         """Parse one XZ stream from a fileobj.
 
diff --git a/src/xz/typing.py b/src/xz/typing.py
index 5d1c722..a327255 100644
--- a/src/xz/typing.py
+++ b/src/xz/typing.py
@@ -1,8 +1,8 @@
 from collections.abc import Mapping, Sequence
 from os import PathLike
-from typing import TYPE_CHECKING, Any, BinaryIO, Literal, Optional, Protocol, Union
+from typing import TYPE_CHECKING, Any, BinaryIO, Literal, Protocol
 
-_LZMAFilenameType = Union[str, bytes, PathLike[str], PathLike[bytes], BinaryIO]
+_LZMAFilenameType = str | bytes | PathLike[str] | PathLike[bytes] | BinaryIO
 
 
 if TYPE_CHECKING:
@@ -10,8 +10,8 @@
     from xz.block import XZBlock
 
 
-_LZMAPresetType = Optional[int]
-_LZMAFiltersType = Optional[Sequence[Mapping[str, Any]]]
+_LZMAPresetType = int | None
+_LZMAFiltersType = Sequence[Mapping[str, Any]] | None
 
 
 # all valid modes if we don't consider changing order nor repetitions
diff --git a/tests/integration/test_file_read.py b/tests/integration/test_file_read.py
index 302a4f1..27c150d 100644
--- a/tests/integration/test_file_read.py
+++ b/tests/integration/test_file_read.py
@@ -14,7 +14,9 @@ def test_read_all(integration_case: _IntegrationCase, data_pattern: bytes) -> No
         pos = 0
         stream_boundaries = []
         block_boundaries = []
-        for stream_item, metadata_stream in zip(streams_items, metadata["streams"]):
+        for stream_item, metadata_stream in zip(
+            streams_items, metadata["streams"], strict=True
+        ):
             stream_boundaries.append(pos)
             stream_pos, stream = stream_item
             assert stream_pos == pos
@@ -22,7 +24,7 @@ def test_read_all(integration_case: _IntegrationCase, data_pattern: bytes) -> No
             block_items = list(stream._fileobjs.items())
             assert len(block_items) == len(metadata_stream["blocks"])
             for block_item, metadata_block in zip(
-                block_items, metadata_stream["blocks"]
+                block_items, metadata_stream["blocks"], strict=True
             ):
                 block_boundaries.append(pos)
                 block_pos, block = block_item
diff --git a/tests/integration/test_ram_usage.py b/tests/integration/test_ram_usage.py
index f6e99a0..39e0dc4 100644
--- a/tests/integration/test_ram_usage.py
+++ b/tests/integration/test_ram_usage.py
@@ -3,7 +3,7 @@
 from lzma import compress
 from pathlib import Path
 from random import randbytes, seed
-from typing import BinaryIO, Optional, cast
+from typing import BinaryIO, cast
 
 import pytest
 
@@ -70,7 +70,7 @@ def test_read_linear(fileobj: BinaryIO, ram_usage: Callable[[], int]) -> None:
 def test_partial_read_each_block(
     fileobj: BinaryIO, ram_usage: Callable[[], int]
 ) -> None:
-    one_block_memory: Optional[int] = None
+    one_block_memory: int | None = None
 
     with XZFile(fileobj) as xz_file:
         for pos in xz_file.block_boundaries[1:]:
@@ -93,7 +93,7 @@ def test_write(tmp_path: Path, ram_usage: Callable[[], int]) -> None:
 
     seed(0)
 
-    one_block_memory: Optional[int] = None
+    one_block_memory: int | None = None
 
     with XZFile(tmp_path / "archive.xz", "w") as xz_file:
         for i in range(nb_blocks):
diff --git a/tests/integration/test_readme.py b/tests/integration/test_readme.py
index 095f37b..7df5ad3 100644
--- a/tests/integration/test_readme.py
+++ b/tests/integration/test_readme.py
@@ -3,7 +3,6 @@
 import os
 from pathlib import Path
 import shutil
-from typing import Optional
 
 import pytest
 
@@ -22,7 +21,7 @@ def change_dir(tmp_path: Path) -> Iterator[None]:
 def _parse_readme() -> list[tuple[int, str]]:
     code_blocks = []
     current_code_block = ""
-    current_code_block_line: Optional[int] = None
+    current_code_block_line: int | None = None
     with (Path(__file__).parent.parent.parent / "README.md").open() as fin:
         for line_no, line in enumerate(fin):
             if line.startswith("```"):
diff --git a/tests/unit/test_attr_proxy.py b/tests/unit/test_attr_proxy.py
index 46508c6..4cefd05 100644
--- a/tests/unit/test_attr_proxy.py
+++ b/tests/unit/test_attr_proxy.py
@@ -1,5 +1,3 @@
-from typing import Optional
-
 import pytest
 
 from xz.utils import AttrProxy
@@ -10,7 +8,7 @@ class Dest:
 
 
 class Src:
-    proxy: Optional[Dest] = None
+    proxy: Dest | None = None
     abc = AttrProxy[str]("proxy")
 
 
diff --git a/tests/unit/test_file.py b/tests/unit/test_file.py
index 9c7641e..09379b8 100644
--- a/tests/unit/test_file.py
+++ b/tests/unit/test_file.py
@@ -2,7 +2,7 @@
 from io import SEEK_END, SEEK_SET, BytesIO, UnsupportedOperation
 import os
 from pathlib import Path
-from typing import Optional, Union, cast
+from typing import cast
 from unittest.mock import Mock, call
 
 import pytest
@@ -115,7 +115,7 @@ def test_read(
     tmp_path: Path,
     data_pattern_locate: Callable[[bytes], tuple[int, int]],
 ) -> None:
-    filename: Union[Path, BytesIO, str]
+    filename: Path | BytesIO | str
 
     if filetype == "fileobj":
         filename = BytesIO(FILE_BYTES)
@@ -186,7 +186,7 @@ def test_read_with_mode(
     tmp_path: Path,
     data_pattern_locate: Callable[[bytes], tuple[int, int]],
 ) -> None:
-    filename: Union[Path, BytesIO]
+    filename: Path | BytesIO
 
     if from_file:
         filename = tmp_path / "archive.xz"
@@ -268,7 +268,7 @@ def test_read_strategy_calls() -> None:
 
 
 @pytest.mark.parametrize("max_block_read_nb", [None, 1, 2, 7, 100])
-def test_read_default_strategy(max_block_read_nb: Optional[int]) -> None:
+def test_read_default_strategy(max_block_read_nb: int | None) -> None:
     fileobj = Mock(wraps=BytesIO(FILE_BYTES_MANY_SMALL_BLOCKS))
 
     max_block_read_nb_ = 8 if max_block_read_nb is None else max_block_read_nb
@@ -432,7 +432,7 @@ def test_write_with_mode(
         "1fb6f37d010000000004595a"  # footer
     )
 
-    filename: Union[Path, BytesIO]
+    filename: Path | BytesIO
 
     if from_file:
         filename = tmp_path / "archive.xz"
diff --git a/tests/unit/test_open.py b/tests/unit/test_open.py
index 4a377cd..0feb7ed 100644
--- a/tests/unit/test_open.py
+++ b/tests/unit/test_open.py
@@ -1,7 +1,6 @@
 from io import BytesIO
 import lzma
 from pathlib import Path
-from typing import Optional
 from unittest.mock import Mock
 
 import pytest
@@ -99,9 +98,7 @@ def test_mode_rt_encoding(encoding: str, expected: str) -> None:
         ),
     ],
 )
-def test_mode_rt_encoding_errors(
-    errors: Optional[str], expected: Optional[str]
-) -> None:
+def test_mode_rt_encoding_errors(errors: str | None, expected: str | None) -> None:
     fileobj = BytesIO(
         bytes.fromhex(
             "fd377a585a000000ff12d9410200210116000000742fe5a301000a656e99636f"
@@ -127,7 +124,7 @@ def test_mode_rt_encoding_errors(
         pytest.param("\r\n", ["a\nb\rc\r\n", "d"], id="'\r\n'"),
     ],
 )
-def test_mode_rt_newline(newline: Optional[str], expected: list[str]) -> None:
+def test_mode_rt_newline(newline: str | None, expected: list[str]) -> None:
     fileobj = BytesIO(
         bytes.fromhex(
             "fd377a585a000000ff12d9410200210116000000742fe5a3010007610a620d63"
@@ -443,7 +440,7 @@ def test_mode_wt_encoding(encoding: str, data: str) -> None:
         ),
     ],
 )
-def test_mode_wt_encoding_errors(errors: Optional[str], data: Optional[bytes]) -> None:
+def test_mode_wt_encoding_errors(errors: str | None, data: bytes | None) -> None:
     fileobj = BytesIO()
 
     with xz_open(fileobj, "wt", errors=errors) as xzfile:
@@ -468,7 +465,7 @@ def test_mode_wt_encoding_errors(errors: Optional[str], data: Optional[bytes]) -
         pytest.param("\r\n", b"a\r\nb\r\n", id="'\r\n'"),
     ],
 )
-def test_mode_wt_newline(newline: Optional[str], data: bytes) -> None:
+def test_mode_wt_newline(newline: str | None, data: bytes) -> None:
     fileobj = BytesIO()
 
     with xz_open(fileobj, "wt", newline=newline) as xzfile:
diff --git a/tox.ini b/tox.ini
index 35b16fd..80ff81f 100644
--- a/tox.ini
+++ b/tox.ini
@@ -2,7 +2,7 @@
 
 [tox]
 envlist =
-    py, py39, py310, py311, py312, py313, py314, pypy3
+    py, py310, py311, py312, py313, py314, pypy3
     build, generate-integration-files, lint, type
 
 [testenv]