diff --git a/.github/workflows/ci-cd.yml b/.github/workflows/ci-cd.yml
index 15b3a8fc..82de1a95 100644
--- a/.github/workflows/ci-cd.yml
+++ b/.github/workflows/ci-cd.yml
@@ -191,6 +191,7 @@ jobs:
     strategy:
       matrix:
         pyver:
+        - 3.13t
         - 3.13
         - 3.12
         - 3.11
@@ -240,7 +241,7 @@ jobs:
 
     - name: Setup Python ${{ matrix.pyver }}
       id: python-install
-      uses: actions/setup-python@v5
+      uses: quansight-labs/setup-python@v5
       with:
         python-version: ${{ matrix.pyver }}
         allow-prereleases: true
@@ -257,7 +258,10 @@ jobs:
     - name: Install dependencies
       uses: py-actions/py-dependency-install@v4
       with:
-        path: requirements/test.txt
+        path: >-
+          requirements/test${{
+            matrix.pyver == '3.13t' && '-freethreading' || ''
+          }}.txt
     - name: Determine pre-compiled compatible wheel
       env:
         # NOTE: When `pip` is forced to colorize output piped into `jq`,
@@ -371,7 +375,8 @@ jobs:
           pytest,
           OS-${{ runner.os }},
           VM-${{ matrix.os }},
-          Py-${{ steps.python-install.outputs.python-version }}
+          Py-${{ steps.python-install.outputs.python-version }}${{
+            matrix.pyver == '3.13t' && 't' || '' }}
         fail_ci_if_error: true
 
   benchmark:
@@ -417,7 +422,7 @@ jobs:
     - name: Install dependencies
       uses: py-actions/py-dependency-install@v4
       with:
-        path: requirements/test.txt
+        path: requirements/codspeed.txt
     - name: Determine pre-compiled compatible wheel
       env:
         # NOTE: When `pip` is forced to colorize output piped into `jq`,
diff --git a/CHANGES/1456.feature.rst b/CHANGES/1456.feature.rst
new file mode 100644
index 00000000..c5da0e04
--- /dev/null
+++ b/CHANGES/1456.feature.rst
@@ -0,0 +1 @@
+Implemented support for the free-threaded build of CPython 3.13 -- by :user:`lysnikolaou`.
diff --git a/CHANGES/1456.packaging.rst b/CHANGES/1456.packaging.rst
new file mode 100644
index 00000000..911a78b2
--- /dev/null
+++ b/CHANGES/1456.packaging.rst
@@ -0,0 +1 @@
+Started building wheels for the free-threaded build of CPython 3.13 -- by :user:`lysnikolaou`.
diff --git a/docs/spelling_wordlist.txt b/docs/spelling_wordlist.txt
index b9339498..95c9c563 100644
--- a/docs/spelling_wordlist.txt
+++ b/docs/spelling_wordlist.txt
@@ -1,5 +1,6 @@
 Bluesky
 Bugfixes
+CPython
 Changelog
 Codecov
 Cython
diff --git a/packaging/pep517_backend/_backend.py b/packaging/pep517_backend/_backend.py
index 9829c043..d5e4f7cd 100644
--- a/packaging/pep517_backend/_backend.py
+++ b/packaging/pep517_backend/_backend.py
@@ -4,6 +4,7 @@
 from __future__ import annotations
 
 import os
+import sysconfig
 import typing as t
 from contextlib import contextmanager, nullcontext, suppress
 from functools import partial
@@ -371,10 +372,12 @@ def get_requires_for_build_wheel(
             stacklevel=999,
         )
 
-    c_ext_build_deps = [] if is_pure_python_build else [
-        'Cython ~= 3.0.0; python_version >= "3.12"',
-        'Cython; python_version < "3.12"',
-    ]
+    if is_pure_python_build:
+        c_ext_build_deps = []
+    elif sysconfig.get_config_var('Py_GIL_DISABLED'):
+        c_ext_build_deps = ['Cython ~= 3.1.0a1']
+    else:
+        c_ext_build_deps = ['Cython ~= 3.0.12']
 
     return _setuptools_get_requires_for_build_wheel(
         config_settings=config_settings,
diff --git a/pyproject.toml b/pyproject.toml
index 81900af5..5a4d0b50 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -64,6 +64,7 @@ linetrace = "True"  # Implies `profile=True`
 
 [tool.cibuildwheel]
 build-frontend = "build"
+enable = ["cpython-freethreading"]
 before-test = [
   # NOTE: Attempt to have pip pre-compile PyYAML wheel with our build
   # NOTE: constraints unset. The hope is that pip will cache that wheel
@@ -91,3 +92,12 @@ pure-python = "false"
 
 [tool.cibuildwheel.windows]
 before-test = []  # Windows cmd has different syntax and pip chooses wheels
+
+# TODO: Remove this when there's a Cython 3.1 final release
+# Remove PIP_CONSTRAINT from the environment
+[[tool.cibuildwheel.overrides]]
+select = "cp313t-*"
+
+test-requires = "-r requirements/test-freethreading.txt"
+inherit.environment = "append"
+environment = {PIP_CONSTRAINT = "requirements/cython-freethreading.txt"}
diff --git a/requirements/codspeed.txt b/requirements/codspeed.txt
new file mode 100644
index 00000000..25cc1722
--- /dev/null
+++ b/requirements/codspeed.txt
@@ -0,0 +1,2 @@
+-r test.txt
+pytest-codspeed==3.2.0
diff --git a/requirements/cython-freethreading.txt b/requirements/cython-freethreading.txt
new file mode 100644
index 00000000..b71204d4
--- /dev/null
+++ b/requirements/cython-freethreading.txt
@@ -0,0 +1 @@
+cython==3.1.0a1
diff --git a/requirements/dev.txt b/requirements/dev.txt
index 2a4069d3..f1d0b300 100644
--- a/requirements/dev.txt
+++ b/requirements/dev.txt
@@ -1,2 +1,2 @@
--r test.txt
+-r codspeed.txt
 -r towncrier.txt
diff --git a/requirements/test-freethreading.txt b/requirements/test-freethreading.txt
new file mode 100644
index 00000000..5919a29f
--- /dev/null
+++ b/requirements/test-freethreading.txt
@@ -0,0 +1,2 @@
+-r cython-freethreading.txt
+-r test-pure.txt
diff --git a/requirements/test-pure.txt b/requirements/test-pure.txt
new file mode 100644
index 00000000..1b7ace2c
--- /dev/null
+++ b/requirements/test-pure.txt
@@ -0,0 +1,8 @@
+covdefaults
+hypothesis>=6.0
+idna==3.10
+multidict==6.1.0
+propcache==0.3.0
+pytest==8.3.5
+pytest-cov>=2.3.1
+pytest-xdist
diff --git a/requirements/test.txt b/requirements/test.txt
index 608feac5..48887360 100644
--- a/requirements/test.txt
+++ b/requirements/test.txt
@@ -1,10 +1,2 @@
 -r cython.txt
-covdefaults
-hypothesis>=6.0
-idna==3.10
-multidict==6.1.0
-propcache==0.3.0
-pytest==8.3.5
-pytest-cov>=2.3.1
-pytest-xdist
-pytest_codspeed==3.2.0
+-r test-pure.txt
diff --git a/tests/test_quoting_benchmarks.py b/tests/test_quoting_benchmarks.py
index fb71b5a5..5e66123a 100644
--- a/tests/test_quoting_benchmarks.py
+++ b/tests/test_quoting_benchmarks.py
@@ -1,6 +1,11 @@
 """codspeed benchmark for yarl._quoting module."""
 
-from pytest_codspeed import BenchmarkFixture
+import pytest
+
+try:
+    from pytest_codspeed import BenchmarkFixture
+except ImportError:  # pragma: no branch  # only hit in cibuildwheel
+    pytestmark = pytest.mark.skip("pytest-codspeed needs to be installed")
 
 from yarl._quoting import _Quoter, _Unquoter
 
@@ -15,70 +20,70 @@
 LONG_QUERY_WITH_PCT = LONG_QUERY + "&d=%25%2F%3F%3A%40%26%3B%3D%2B"
 
 
-def test_quote_query_string(benchmark: BenchmarkFixture) -> None:
+def test_quote_query_string(benchmark: "BenchmarkFixture") -> None:
     @benchmark
     def _run() -> None:
         for _ in range(100):
             QUERY_QUOTER("a=1&b=2&c=3&d=4&e=5&f=6&g=7&h=8&i=9&j=0")
 
 
-def test_quoter_ascii(benchmark: BenchmarkFixture) -> None:
+def test_quoter_ascii(benchmark: "BenchmarkFixture") -> None:
     @benchmark
     def _run() -> None:
         for _ in range(100):
             QUOTER_SLASH_SAFE("/path/to")
 
 
-def test_quote_long_path(benchmark: BenchmarkFixture) -> None:
+def test_quote_long_path(benchmark: "BenchmarkFixture") -> None:
     @benchmark
     def _run() -> None:
         for _ in range(100):
             PATH_QUOTER(LONG_PATH)
 
 
-def test_quoter_pct(benchmark: BenchmarkFixture) -> None:
+def test_quoter_pct(benchmark: "BenchmarkFixture") -> None:
     @benchmark
     def _run() -> None:
         for _ in range(100):
             QUOTER("abc%0a")
 
 
-def test_long_query(benchmark: BenchmarkFixture) -> None:
+def test_long_query(benchmark: "BenchmarkFixture") -> None:
     @benchmark
     def _run() -> None:
         for _ in range(100):
             QUERY_QUOTER(LONG_QUERY)
 
 
-def test_long_query_with_pct(benchmark: BenchmarkFixture) -> None:
+def test_long_query_with_pct(benchmark: "BenchmarkFixture") -> None:
     @benchmark
     def _run() -> None:
         for _ in range(100):
             QUERY_QUOTER(LONG_QUERY_WITH_PCT)
 
 
-def test_quoter_quote_utf8(benchmark: BenchmarkFixture) -> None:
+def test_quoter_quote_utf8(benchmark: "BenchmarkFixture") -> None:
     @benchmark
     def _run() -> None:
         for _ in range(100):
             PATH_QUOTER("/шлях/файл")
 
 
-def test_unquoter_short(benchmark: BenchmarkFixture) -> None:
+def test_unquoter_short(benchmark: "BenchmarkFixture") -> None:
     @benchmark
     def _run() -> None:
         for _ in range(100):
             UNQUOTER("/path/to")
 
 
-def test_unquoter_long_ascii(benchmark: BenchmarkFixture) -> None:
+def test_unquoter_long_ascii(benchmark: "BenchmarkFixture") -> None:
     @benchmark
     def _run() -> None:
         for _ in range(100):
             UNQUOTER(LONG_QUERY)
 
 
-def test_unquoter_long_pct(benchmark: BenchmarkFixture) -> None:
+def test_unquoter_long_pct(benchmark: "BenchmarkFixture") -> None:
     @benchmark
     def _run() -> None:
         for _ in range(100):
diff --git a/tests/test_url_benchmarks.py b/tests/test_url_benchmarks.py
index c8ae1055..3847dc42 100644
--- a/tests/test_url_benchmarks.py
+++ b/tests/test_url_benchmarks.py
@@ -1,6 +1,11 @@
 """codspeed benchmarks for yarl.URL."""
 
-from pytest_codspeed import BenchmarkFixture
+import pytest
+
+try:
+    from pytest_codspeed import BenchmarkFixture
+except ImportError:  # pragma: no branch  # only hit in cibuildwheel
+    pytestmark = pytest.mark.skip("pytest-codspeed needs to be installed")
 
 from yarl import URL
 
@@ -29,49 +34,59 @@ class _SubClassedStr(str):
     """A subclass of str that does nothing."""
 
 
-def test_url_build_with_host_and_port(benchmark: BenchmarkFixture) -> None:
+def test_url_build_with_host_and_port(
+    benchmark: "BenchmarkFixture",
+) -> None:
     @benchmark
     def _run() -> None:
         for _ in range(100):
             URL.build(host="www.domain.tld", path="/req", port=1234)
 
 
-def test_url_build_with_simple_query(benchmark: BenchmarkFixture) -> None:
+def test_url_build_with_simple_query(
+    benchmark: "BenchmarkFixture",
+) -> None:
     @benchmark
     def _run() -> None:
         for _ in range(100):
             URL.build(host="www.domain.tld", query=SIMPLE_QUERY)
 
 
-def test_url_build_no_netloc(benchmark: BenchmarkFixture) -> None:
+def test_url_build_no_netloc(benchmark: "BenchmarkFixture") -> None:
     @benchmark
     def _run() -> None:
         for _ in range(100):
             URL.build(path="/req/req/req")
 
 
-def test_url_build_no_netloc_relative(benchmark: BenchmarkFixture) -> None:
+def test_url_build_no_netloc_relative(
+    benchmark: "BenchmarkFixture",
+) -> None:
     @benchmark
     def _run() -> None:
         for _ in range(100):
             URL.build(path="req/req/req")
 
 
-def test_url_build_encoded_with_host_and_port(benchmark: BenchmarkFixture) -> None:
+def test_url_build_encoded_with_host_and_port(
+    benchmark: "BenchmarkFixture",
+) -> None:
     @benchmark
     def _run() -> None:
         for _ in range(100):
             URL.build(host="www.domain.tld", path="/req", port=1234, encoded=True)
 
 
-def test_url_build_with_host(benchmark: BenchmarkFixture) -> None:
+def test_url_build_with_host(benchmark: "BenchmarkFixture") -> None:
     @benchmark
     def _run() -> None:
         for _ in range(100):
             URL.build(host="domain")
 
 
-def test_url_build_access_username_password(benchmark: BenchmarkFixture) -> None:
+def test_url_build_access_username_password(
+    benchmark: "BenchmarkFixture",
+) -> None:
     @benchmark
     def _run() -> None:
         for _ in range(100):
@@ -80,7 +95,9 @@ def _run() -> None:
             url.raw_password
 
 
-def test_url_build_access_raw_host(benchmark: BenchmarkFixture) -> None:
+def test_url_build_access_raw_host(
+    benchmark: "BenchmarkFixture",
+) -> None:
     @benchmark
     def _run() -> None:
         for _ in range(100):
@@ -88,7 +105,9 @@ def _run() -> None:
             url.raw_host
 
 
-def test_url_build_access_fragment(benchmark: BenchmarkFixture) -> None:
+def test_url_build_access_fragment(
+    benchmark: "BenchmarkFixture",
+) -> None:
     @benchmark
     def _run() -> None:
         for _ in range(100):
@@ -96,7 +115,9 @@ def _run() -> None:
             url.fragment
 
 
-def test_url_build_access_raw_path(benchmark: BenchmarkFixture) -> None:
+def test_url_build_access_raw_path(
+    benchmark: "BenchmarkFixture",
+) -> None:
     @benchmark
     def _run() -> None:
         for _ in range(100):
@@ -104,77 +125,97 @@ def _run() -> None:
             url.raw_path
 
 
-def test_url_build_with_different_hosts(benchmark: BenchmarkFixture) -> None:
+def test_url_build_with_different_hosts(
+    benchmark: "BenchmarkFixture",
+) -> None:
     @benchmark
     def _run() -> None:
         for host in MANY_HOSTS:
             URL.build(host=host)
 
 
-def test_url_build_with_host_path_and_port(benchmark: BenchmarkFixture) -> None:
+def test_url_build_with_host_path_and_port(
+    benchmark: "BenchmarkFixture",
+) -> None:
     @benchmark
     def _run() -> None:
         for _ in range(100):
             URL.build(host="www.domain.tld", port=1234)
 
 
-def test_url_make_no_netloc(benchmark: BenchmarkFixture) -> None:
+def test_url_make_no_netloc(benchmark: "BenchmarkFixture") -> None:
     @benchmark
     def _run() -> None:
         for _ in range(100):
             URL("/req/req/req")
 
 
-def test_url_make_no_netloc_relative(benchmark: BenchmarkFixture) -> None:
+def test_url_make_no_netloc_relative(
+    benchmark: "BenchmarkFixture",
+) -> None:
     @benchmark
     def _run() -> None:
         for _ in range(100):
             URL("req/req/req")
 
 
-def test_url_make_with_host_path_and_port(benchmark: BenchmarkFixture) -> None:
+def test_url_make_with_host_path_and_port(
+    benchmark: "BenchmarkFixture",
+) -> None:
     @benchmark
     def _run() -> None:
         for _ in range(100):
             URL("http://www.domain.tld:1234/req")
 
 
-def test_url_make_encoded_with_host_path_and_port(benchmark: BenchmarkFixture) -> None:
+def test_url_make_encoded_with_host_path_and_port(
+    benchmark: "BenchmarkFixture",
+) -> None:
     @benchmark
     def _run() -> None:
         for _ in range(100):
             URL("http://www.domain.tld:1234/req", encoded=True)
 
 
-def test_url_make_with_host_and_path(benchmark: BenchmarkFixture) -> None:
+def test_url_make_with_host_and_path(
+    benchmark: "BenchmarkFixture",
+) -> None:
     @benchmark
     def _run() -> None:
         for _ in range(100):
             URL("http://www.domain.tld")
 
 
-def test_url_make_with_many_hosts(benchmark: BenchmarkFixture) -> None:
+def test_url_make_with_many_hosts(
+    benchmark: "BenchmarkFixture",
+) -> None:
     @benchmark
     def _run() -> None:
         for url in MANY_URLS:
             URL(url)
 
 
-def test_url_make_with_many_ipv4_hosts(benchmark: BenchmarkFixture) -> None:
+def test_url_make_with_many_ipv4_hosts(
+    benchmark: "BenchmarkFixture",
+) -> None:
     @benchmark
     def _run() -> None:
         for url in MANY_IPV4_URLS:
             URL(url)
 
 
-def test_url_make_with_many_ipv6_hosts(benchmark: BenchmarkFixture) -> None:
+def test_url_make_with_many_ipv6_hosts(
+    benchmark: "BenchmarkFixture",
+) -> None:
     @benchmark
     def _run() -> None:
         for url in MANY_IPV6_URLS:
             URL(url)
 
 
-def test_url_make_access_raw_host(benchmark: BenchmarkFixture) -> None:
+def test_url_make_access_raw_host(
+    benchmark: "BenchmarkFixture",
+) -> None:
     @benchmark
     def _run() -> None:
         for _ in range(100):
@@ -182,7 +223,7 @@ def _run() -> None:
             url.raw_host
 
 
-def test_raw_host_empty_cache(benchmark: BenchmarkFixture) -> None:
+def test_raw_host_empty_cache(benchmark: "BenchmarkFixture") -> None:
     url = URL("http://www.domain.tld")
 
     @benchmark
@@ -192,7 +233,9 @@ def _run() -> None:
             url.raw_host
 
 
-def test_url_make_access_fragment(benchmark: BenchmarkFixture) -> None:
+def test_url_make_access_fragment(
+    benchmark: "BenchmarkFixture",
+) -> None:
     @benchmark
     def _run() -> None:
         for _ in range(100):
@@ -200,7 +243,9 @@ def _run() -> None:
             url.fragment
 
 
-def test_url_make_access_raw_path(benchmark: BenchmarkFixture) -> None:
+def test_url_make_access_raw_path(
+    benchmark: "BenchmarkFixture",
+) -> None:
     @benchmark
     def _run() -> None:
         for _ in range(100):
@@ -208,7 +253,9 @@ def _run() -> None:
             url.raw_path
 
 
-def test_url_make_access_username_password(benchmark: BenchmarkFixture) -> None:
+def test_url_make_access_username_password(
+    benchmark: "BenchmarkFixture",
+) -> None:
     @benchmark
     def _run() -> None:
         for _ in range(100):
@@ -217,49 +264,59 @@ def _run() -> None:
             url.raw_password
 
 
-def test_url_make_empty_username(benchmark: BenchmarkFixture) -> None:
+def test_url_make_empty_username(benchmark: "BenchmarkFixture") -> None:
     @benchmark
     def _run() -> None:
         for _ in range(100):
             URL("http://:password@www.domain.tld")
 
 
-def test_url_make_empty_password(benchmark: BenchmarkFixture) -> None:
+def test_url_make_empty_password(benchmark: "BenchmarkFixture") -> None:
     @benchmark
     def _run() -> None:
         for _ in range(100):
             URL("http://user:@www.domain.tld")
 
 
-def test_url_make_with_ipv4_address_path_and_port(benchmark: BenchmarkFixture) -> None:
+def test_url_make_with_ipv4_address_path_and_port(
+    benchmark: "BenchmarkFixture",
+) -> None:
     @benchmark
     def _run() -> None:
         for _ in range(100):
             URL("http://127.0.0.1:1234/req")
 
 
-def test_url_make_with_ipv4_address_and_path(benchmark: BenchmarkFixture) -> None:
+def test_url_make_with_ipv4_address_and_path(
+    benchmark: "BenchmarkFixture",
+) -> None:
     @benchmark
     def _run() -> None:
         for _ in range(100):
             URL("http://127.0.0.1/req")
 
 
-def test_url_make_with_ipv6_address_path_and_port(benchmark: BenchmarkFixture) -> None:
+def test_url_make_with_ipv6_address_path_and_port(
+    benchmark: "BenchmarkFixture",
+) -> None:
     @benchmark
     def _run() -> None:
         for _ in range(100):
             URL("http://[::1]:1234/req")
 
 
-def test_url_make_with_ipv6_address_and_path(benchmark: BenchmarkFixture) -> None:
+def test_url_make_with_ipv6_address_and_path(
+    benchmark: "BenchmarkFixture",
+) -> None:
     @benchmark
     def _run() -> None:
         for _ in range(100):
             URL("http://[::1]/req")
 
 
-def test_extend_query_subclassed_str(benchmark: BenchmarkFixture) -> None:
+def test_extend_query_subclassed_str(
+    benchmark: "BenchmarkFixture",
+) -> None:
     """Test extending a query with a subclassed str."""
     subclassed_query = {str(i): _SubClassedStr(i) for i in range(10)}
 
@@ -269,84 +326,94 @@ def _run() -> None:
             BASE_URL.with_query(subclassed_query)
 
 
-def test_with_query_mapping(benchmark: BenchmarkFixture) -> None:
+def test_with_query_mapping(benchmark: "BenchmarkFixture") -> None:
     @benchmark
     def _run() -> None:
         for _ in range(25):
             BASE_URL.with_query(SIMPLE_QUERY)
 
 
-def test_with_query_mapping_int_values(benchmark: BenchmarkFixture) -> None:
+def test_with_query_mapping_int_values(
+    benchmark: "BenchmarkFixture",
+) -> None:
     @benchmark
     def _run() -> None:
         for _ in range(25):
             BASE_URL.with_query(SIMPLE_INT_QUERY)
 
 
-def test_with_query_sequence_mapping(benchmark: BenchmarkFixture) -> None:
+def test_with_query_sequence_mapping(
+    benchmark: "BenchmarkFixture",
+) -> None:
     @benchmark
     def _run() -> None:
         for _ in range(25):
             BASE_URL.with_query(QUERY_SEQ)
 
 
-def test_with_query_empty(benchmark: BenchmarkFixture) -> None:
+def test_with_query_empty(benchmark: "BenchmarkFixture") -> None:
     @benchmark
     def _run() -> None:
         for _ in range(25):
             BASE_URL.with_query({})
 
 
-def test_with_query_none(benchmark: BenchmarkFixture) -> None:
+def test_with_query_none(benchmark: "BenchmarkFixture") -> None:
     @benchmark
     def _run() -> None:
         for _ in range(25):
             BASE_URL.with_query(None)
 
 
-def test_update_query_mapping(benchmark: BenchmarkFixture) -> None:
+def test_update_query_mapping(benchmark: "BenchmarkFixture") -> None:
     @benchmark
     def _run() -> None:
         for _ in range(25):
             BASE_URL.update_query(SIMPLE_QUERY)
 
 
-def test_update_query_mapping_with_existing_query(benchmark: BenchmarkFixture) -> None:
+def test_update_query_mapping_with_existing_query(
+    benchmark: "BenchmarkFixture",
+) -> None:
     @benchmark
     def _run() -> None:
         for _ in range(25):
             QUERY_URL.update_query(SIMPLE_QUERY)
 
 
-def test_update_query_sequence_mapping(benchmark: BenchmarkFixture) -> None:
+def test_update_query_sequence_mapping(
+    benchmark: "BenchmarkFixture",
+) -> None:
     @benchmark
     def _run() -> None:
         for _ in range(25):
             BASE_URL.update_query(QUERY_SEQ)
 
 
-def test_update_query_empty(benchmark: BenchmarkFixture) -> None:
+def test_update_query_empty(benchmark: "BenchmarkFixture") -> None:
     @benchmark
     def _run() -> None:
         for _ in range(25):
             BASE_URL.update_query({})
 
 
-def test_update_query_none(benchmark: BenchmarkFixture) -> None:
+def test_update_query_none(benchmark: "BenchmarkFixture") -> None:
     @benchmark
     def _run() -> None:
         for _ in range(25):
             BASE_URL.update_query(None)
 
 
-def test_update_query_string(benchmark: BenchmarkFixture) -> None:
+def test_update_query_string(benchmark: "BenchmarkFixture") -> None:
     @benchmark
     def _run() -> None:
         for _ in range(25):
             BASE_URL.update_query(QUERY_STRING)
 
 
-def test_url_extend_query_simple_query_dict(benchmark: BenchmarkFixture) -> None:
+def test_url_extend_query_simple_query_dict(
+    benchmark: "BenchmarkFixture",
+) -> None:
     @benchmark
     def _run() -> None:
         for _ in range(25):
@@ -354,7 +421,7 @@ def _run() -> None:
 
 
 def test_url_extend_query_existing_query_simple_query_dict(
-    benchmark: BenchmarkFixture,
+    benchmark: "BenchmarkFixture",
 ) -> None:
     @benchmark
     def _run() -> None:
@@ -362,91 +429,95 @@ def _run() -> None:
             QUERY_URL.extend_query(SIMPLE_QUERY)
 
 
-def test_url_extend_query_existing_query_string(benchmark: BenchmarkFixture) -> None:
+def test_url_extend_query_existing_query_string(
+    benchmark: "BenchmarkFixture",
+) -> None:
     @benchmark
     def _run() -> None:
         for _ in range(25):
             QUERY_URL.extend_query(QUERY_STRING)
 
 
-def test_url_to_string(benchmark: BenchmarkFixture) -> None:
+def test_url_to_string(benchmark: "BenchmarkFixture") -> None:
     @benchmark
     def _run() -> None:
         for _ in range(100):
             str(BASE_URL)
 
 
-def test_url_with_path_to_string(benchmark: BenchmarkFixture) -> None:
+def test_url_with_path_to_string(benchmark: "BenchmarkFixture") -> None:
     @benchmark
     def _run() -> None:
         for _ in range(100):
             str(URL_WITH_PATH)
 
 
-def test_url_with_query_to_string(benchmark: BenchmarkFixture) -> None:
+def test_url_with_query_to_string(
+    benchmark: "BenchmarkFixture",
+) -> None:
     @benchmark
     def _run() -> None:
         for _ in range(100):
             str(QUERY_URL)
 
 
-def test_url_with_fragment(benchmark: BenchmarkFixture) -> None:
+def test_url_with_fragment(benchmark: "BenchmarkFixture") -> None:
     @benchmark
     def _run() -> None:
         for _ in range(100):
             BASE_URL.with_fragment("fragment")
 
 
-def test_url_with_user(benchmark: BenchmarkFixture) -> None:
+def test_url_with_user(benchmark: "BenchmarkFixture") -> None:
     @benchmark
     def _run() -> None:
         for _ in range(100):
             BASE_URL.with_user("user")
 
 
-def test_url_with_password(benchmark: BenchmarkFixture) -> None:
+def test_url_with_password(benchmark: "BenchmarkFixture") -> None:
     @benchmark
     def _run() -> None:
         for _ in range(100):
             BASE_URL.with_password("password")
 
 
-def test_url_with_host(benchmark: BenchmarkFixture) -> None:
+def test_url_with_host(benchmark: "BenchmarkFixture") -> None:
     @benchmark
     def _run() -> None:
         for _ in range(100):
             BASE_URL.with_host("www.domain.tld")
 
 
-def test_url_with_port(benchmark: BenchmarkFixture) -> None:
+def test_url_with_port(benchmark: "BenchmarkFixture") -> None:
     @benchmark
     def _run() -> None:
         for _ in range(100):
             BASE_URL.with_port(1234)
 
 
-def test_url_with_scheme(benchmark: BenchmarkFixture) -> None:
+def test_url_with_scheme(benchmark: "BenchmarkFixture") -> None:
     @benchmark
     def _run() -> None:
         for _ in range(100):
             BASE_URL.with_scheme("https")
 
 
-def test_url_with_name(benchmark: BenchmarkFixture) -> None:
+def test_url_with_name(benchmark: "BenchmarkFixture") -> None:
     @benchmark
     def _run() -> None:
         for _ in range(100):
             BASE_URL.with_name("other.tld")
 
 
-def test_url_with_path(benchmark: BenchmarkFixture) -> None:
+def test_url_with_path(benchmark: "BenchmarkFixture") -> None:
     @benchmark
     def _run() -> None:
         for _ in range(100):
             BASE_URL.with_path("/req")
 
 
-def test_url_origin(benchmark: BenchmarkFixture) -> None:
+def test_url_origin(benchmark: "BenchmarkFixture") -> None:
     urls = [URL(BASE_URL_STR) for _ in range(100)]
 
     @benchmark
@@ -455,7 +526,9 @@ def _run() -> None:
             url.origin()
 
 
-def test_url_origin_with_user_pass(benchmark: BenchmarkFixture) -> None:
+def test_url_origin_with_user_pass(
+    benchmark: "BenchmarkFixture",
+) -> None:
     urls = [URL(URL_WITH_USER_PASS_STR) for _ in range(100)]
 
     @benchmark
@@ -464,7 +537,7 @@ def _run() -> None:
             url.origin()
 
 
-def test_url_with_path_origin(benchmark: BenchmarkFixture) -> None:
+def test_url_with_path_origin(benchmark: "BenchmarkFixture") -> None:
     urls = [URL(URL_WITH_PATH_STR) for _ in range(100)]
 
     @benchmark
@@ -473,14 +546,14 @@ def _run() -> None:
             url.origin()
 
 
-def test_url_with_path_relative(benchmark: BenchmarkFixture) -> None:
+def test_url_with_path_relative(benchmark: "BenchmarkFixture") -> None:
     @benchmark
     def _run() -> None:
         for _ in range(100):
             URL_WITH_PATH.relative()
 
 
-def test_url_with_path_parent(benchmark: BenchmarkFixture) -> None:
+def test_url_with_path_parent(benchmark: "BenchmarkFixture") -> None:
     cache = URL_WITH_PATH._cache
 
     @benchmark
@@ -490,21 +563,23 @@ def _run() -> None:
             URL_WITH_PATH.parent
 
 
-def test_url_join(benchmark: BenchmarkFixture) -> None:
+def test_url_join(benchmark: "BenchmarkFixture") -> None:
     @benchmark
     def _run() -> None:
         for _ in range(100):
             BASE_URL.join(REL_URL)
 
 
-def test_url_joinpath_encoded(benchmark: BenchmarkFixture) -> None:
+def test_url_joinpath_encoded(benchmark: "BenchmarkFixture") -> None:
     @benchmark
     def _run() -> None:
         for _ in range(100):
             BASE_URL.joinpath("req", encoded=True)
 
 
-def test_url_joinpath_encoded_long(benchmark: BenchmarkFixture) -> None:
+def test_url_joinpath_encoded_long(
+    benchmark: "BenchmarkFixture",
+) -> None:
     @benchmark
     def _run() -> None:
         for _ in range(100):
@@ -513,21 +588,23 @@ def _run() -> None:
             )
 
 
-def test_url_joinpath(benchmark: BenchmarkFixture) -> None:
+def test_url_joinpath(benchmark: "BenchmarkFixture") -> None:
     @benchmark
     def _run() -> None:
         for _ in range(100):
             BASE_URL.joinpath("req", encoded=False)
 
 
-def test_url_joinpath_with_truediv(benchmark: BenchmarkFixture) -> None:
+def test_url_joinpath_with_truediv(
+    benchmark: "BenchmarkFixture",
+) -> None:
     @benchmark
     def _run() -> None:
         for _ in range(100):
             BASE_URL / "req/req/req"
 
 
-def test_url_equality(benchmark: BenchmarkFixture) -> None:
+def test_url_equality(benchmark: "BenchmarkFixture") -> None:
     @benchmark
     def _run() -> None:
         for _ in range(100):
@@ -536,7 +613,7 @@ def _run() -> None:
             URL_WITH_PATH == URL_WITH_PATH
 
 
-def test_url_hash(benchmark: BenchmarkFixture) -> None:
+def test_url_hash(benchmark: "BenchmarkFixture") -> None:
     cache = BASE_URL._cache
 
     @benchmark
@@ -546,7 +623,7 @@ def _run() -> None:
             hash(BASE_URL)
 
 
-def test_is_default_port(benchmark: BenchmarkFixture) -> None:
+def test_is_default_port(benchmark: "BenchmarkFixture") -> None:
     @benchmark
     def _run() -> None:
         for _ in range(100):
@@ -554,7 +631,7 @@ def _run() -> None:
             URL_WITH_NOT_DEFAULT_PORT.is_default_port()
 
 
-def test_human_repr(benchmark: BenchmarkFixture) -> None:
+def test_human_repr(benchmark: "BenchmarkFixture") -> None:
     @benchmark
     def _run() -> None:
         for _ in range(100):
@@ -566,7 +643,7 @@ def _run() -> None:
             REL_URL.human_repr()
 
 
-def test_query_string(benchmark: BenchmarkFixture) -> None:
+def test_query_string(benchmark: "BenchmarkFixture") -> None:
     urls = [URL(QUERY_URL_STR) for _ in range(100)]
 
     @benchmark
@@ -575,7 +652,7 @@ def _run() -> None:
             url.query_string
 
 
-def test_empty_query_string(benchmark: BenchmarkFixture) -> None:
+def test_empty_query_string(benchmark: "BenchmarkFixture") -> None:
     urls = [URL(BASE_URL_STR) for _ in range(100)]
 
     @benchmark
@@ -584,7 +661,9 @@ def _run() -> None:
             url.query_string
 
 
-def test_empty_query_string_uncached(benchmark: BenchmarkFixture) -> None:
+def test_empty_query_string_uncached(
+    benchmark: "BenchmarkFixture",
+) -> None:
     urls = [URL(BASE_URL_STR) for _ in range(100)]
 
     @benchmark
@@ -593,7 +672,7 @@ def _run() -> None:
             URL.query_string.wrapped(url)
 
 
-def test_query(benchmark: BenchmarkFixture) -> None:
+def test_query(benchmark: "BenchmarkFixture") -> None:
     urls = [URL(QUERY_URL_STR) for _ in range(100)]
 
     @benchmark
@@ -602,7 +681,7 @@ def _run() -> None:
             url.query
 
 
-def test_empty_query(benchmark: BenchmarkFixture) -> None:
+def test_empty_query(benchmark: "BenchmarkFixture") -> None:
     urls = [URL(BASE_URL_STR) for _ in range(100)]
 
     @benchmark
@@ -611,7 +690,9 @@ def _run() -> None:
             url.query
 
 
-def test_url_host_port_subcomponent(benchmark: BenchmarkFixture) -> None:
+def test_url_host_port_subcomponent(
+    benchmark: "BenchmarkFixture",
+) -> None:
     cache_non_default = URL_WITH_NOT_DEFAULT_PORT._cache
     cache = BASE_URL._cache
 
@@ -624,7 +705,7 @@ def _run() -> None:
             BASE_URL.host_port_subcomponent
 
 
-def test_empty_path(benchmark: BenchmarkFixture) -> None:
+def test_empty_path(benchmark: "BenchmarkFixture") -> None:
     """Test accessing empty path."""
 
     @benchmark
@@ -633,7 +714,7 @@ def _run() -> None:
             BASE_URL.path
 
 
-def test_empty_path_uncached(benchmark: BenchmarkFixture) -> None:
+def test_empty_path_uncached(benchmark: "BenchmarkFixture") -> None:
     """Test accessing empty path without cache."""
 
     @benchmark
@@ -642,7 +723,7 @@ def _run() -> None:
             URL.path.wrapped(BASE_URL)
 
 
-def test_empty_path_safe(benchmark: BenchmarkFixture) -> None:
+def test_empty_path_safe(benchmark: "BenchmarkFixture") -> None:
     """Test accessing empty path safe."""
 
     @benchmark
@@ -651,7 +732,9 @@ def _run() -> None:
             BASE_URL.path_safe
 
 
-def test_empty_path_safe_uncached(benchmark: BenchmarkFixture) -> None:
+def test_empty_path_safe_uncached(
+    benchmark: "BenchmarkFixture",
+) -> None:
     """Test accessing empty path safe without cache."""
 
     @benchmark
@@ -660,7 +743,7 @@ def _run() -> None:
             URL.path_safe.wrapped(BASE_URL)
 
 
-def test_path_safe(benchmark: BenchmarkFixture) -> None:
+def test_path_safe(benchmark: "BenchmarkFixture") -> None:
     """Test accessing path safe."""
 
     @benchmark
@@ -669,7 +752,7 @@ def _run() -> None:
             URL_WITH_PATH.path_safe
 
 
-def test_path_safe_uncached(benchmark: BenchmarkFixture) -> None:
+def test_path_safe_uncached(benchmark: "BenchmarkFixture") -> None:
     """Test accessing path safe without cache."""
 
     @benchmark
@@ -678,7 +761,7 @@ def _run() -> None:
             URL.path_safe.wrapped(URL_WITH_PATH)
 
 
-def test_empty_raw_path_qs(benchmark: BenchmarkFixture) -> None:
+def test_empty_raw_path_qs(benchmark: "BenchmarkFixture") -> None:
     """Test accessing empty raw path with query."""
 
     @benchmark
@@ -687,7 +770,9 @@ def _run() -> None:
             BASE_URL.raw_path_qs
 
 
-def test_empty_raw_path_qs_uncached(benchmark: BenchmarkFixture) -> None:
+def test_empty_raw_path_qs_uncached(
+    benchmark: "BenchmarkFixture",
+) -> None:
     """Test accessing empty raw path with query without cache."""
 
     @benchmark
@@ -696,7 +781,7 @@ def _run() -> None:
             URL.raw_path_qs.wrapped(BASE_URL)
 
 
-def test_raw_path_qs(benchmark: BenchmarkFixture) -> None:
+def test_raw_path_qs(benchmark: "BenchmarkFixture") -> None:
     """Test accessing raw path qs without query."""
 
     @benchmark
@@ -705,7 +790,7 @@ def _run() -> None:
             URL_WITH_PATH.raw_path_qs
 
 
-def test_raw_path_qs_uncached(benchmark: BenchmarkFixture) -> None:
+def test_raw_path_qs_uncached(benchmark: "BenchmarkFixture") -> None:
     """Test accessing raw path qs without query and without cache."""
 
     @benchmark
@@ -714,7 +799,7 @@ def _run() -> None:
             URL.raw_path_qs.wrapped(URL_WITH_PATH)
 
 
-def test_raw_path_qs_with_query(benchmark: BenchmarkFixture) -> None:
+def test_raw_path_qs_with_query(benchmark: "BenchmarkFixture") -> None:
     """Test accessing raw path qs with query."""
 
     @benchmark
@@ -723,7 +808,9 @@ def _run() -> None:
             IPV6_QUERY_URL.raw_path_qs
 
 
-def test_raw_path_qs_with_query_uncached(benchmark: BenchmarkFixture) -> None:
+def test_raw_path_qs_with_query_uncached(
+    benchmark: "BenchmarkFixture",
+) -> None:
     """Test accessing raw path qs with query and without cache."""
 
     @benchmark
diff --git a/yarl/_quoting_c.pyx b/yarl/_quoting_c.pyx
index 067ba96e..5b35fff8 100644
--- a/yarl/_quoting_c.pyx
+++ b/yarl/_quoting_c.pyx
@@ -1,4 +1,4 @@
-# cython: language_level=3
+# cython: language_level=3, freethreading_compatible=True
 
 from cpython.exc cimport PyErr_NoMemory
 from cpython.mem cimport PyMem_Free, PyMem_Malloc, PyMem_Realloc
@@ -13,6 +13,7 @@ from cpython.unicode cimport (
 from libc.stdint cimport uint8_t, uint64_t
 from libc.string cimport memcpy, memset
 
+import sysconfig
 from string import ascii_letters, digits
 
 
@@ -26,6 +27,7 @@ cdef str QS = '+&=;'
 
 DEF BUF_SIZE = 8 * 1024  # 8KiB
 cdef char BUFFER[BUF_SIZE]
+cdef bint IS_GIL_DISABLED = sysconfig.get_config_var("Py_GIL_DISABLED")
 
 cdef inline Py_UCS4 _to_hex(uint8_t v) noexcept:
     if v < 10:
@@ -49,14 +51,14 @@ cdef inline int _is_lower_hex(Py_UCS4 v) noexcept:
     return 'a' <= v <= 'f'
 
 
-cdef inline Py_UCS4 _restore_ch(Py_UCS4 d1, Py_UCS4 d2):
+cdef inline long _restore_ch(Py_UCS4 d1, Py_UCS4 d2):
     cdef int digit1 = _from_hex(d1)
     if digit1 < 0:
-        return <Py_UCS4>-1
+        return -1
     cdef int digit2 = _from_hex(d2)
     if digit2 < 0:
-        return <Py_UCS4>-1
-    return <Py_UCS4>(digit1 << 4 | digit2)
+        return -1
+    return digit1 << 4 | digit2
 
 
 cdef uint8_t ALLOWED_TABLE[16]
@@ -91,7 +93,15 @@ cdef struct Writer:
 
 
 cdef inline void _init_writer(Writer* writer):
-    writer.buf = &BUFFER[0]
+    cdef char *buf
+    if IS_GIL_DISABLED:
+        buf = <char *> PyMem_Malloc(BUF_SIZE)
+        if buf == NULL:
+            PyErr_NoMemory()
+            return
+        writer.buf = buf
+    else:
+        writer.buf = &BUFFER[0]
     writer.size = BUF_SIZE
     writer.pos = 0
     writer.changed = 0
@@ -255,6 +265,7 @@ cdef class _Quoter:
         Writer *writer
     ):
         cdef Py_UCS4 ch
+        cdef long chl
         cdef int changed
         cdef Py_ssize_t idx = 0
 
@@ -262,11 +273,12 @@ cdef class _Quoter:
             ch = PyUnicode_READ(kind, data, idx)
             idx += 1
             if ch == '%' and self._requote and idx <= length - 2:
-                ch = _restore_ch(
+                chl = _restore_ch(
                     PyUnicode_READ(kind, data, idx),
                     PyUnicode_READ(kind, data, idx + 1)
                 )
-                if ch != <Py_UCS4>-1:
+                if chl != -1:
+                    ch = <Py_UCS4>chl
                     idx += 2
                     if ch < 128:
                         if bit_at(self._protected_table, ch):
@@ -342,6 +354,7 @@ cdef class _Unquoter:
         cdef Py_ssize_t consumed
         cdef str unquoted
         cdef Py_UCS4 ch = 0
+        cdef long chl = 0
         cdef Py_ssize_t idx = 0
         cdef Py_ssize_t start_pct
         cdef int kind = PyUnicode_KIND(val)
@@ -352,11 +365,12 @@ cdef class _Unquoter:
             idx += 1
             if ch == '%' and idx <= length - 2:
                 changed = 1
-                ch = _restore_ch(
+                chl = _restore_ch(
                     PyUnicode_READ(kind, data, idx),
                     PyUnicode_READ(kind, data, idx + 1)
                 )
-                if ch != <Py_UCS4>-1:
+                if chl != -1:
+                    ch = <Py_UCS4>chl
                     idx += 2
                     assert buflen < 4
                     buffer[buflen] = ch