msgpack.diff

diff --git a/setup.py b/setup.py
index 4029e9e..c855180 100644
--- a/setup.py
+++ b/setup.py
@@ -3,6 +3,9 @@ import os
 import sys
 
 from setuptools import Extension, setup
+from Cython.Build import cythonize
+from Cython.Compiler.Version import version as cython_version
+from packaging.version import Version
 
 PYPY = hasattr(sys, "pypy_version_info")
 
@@ -18,7 +21,7 @@ if not PYPY and not os.environ.get("MSGPACK_PUREPYTHON"):
     ext_modules.append(
         Extension(
             "msgpack._cmsgpack",
-            sources=["msgpack/_cmsgpack.c"],
+            sources=["msgpack/_cmsgpack.pyx"],
             libraries=libraries,
             include_dirs=["."],
             define_macros=macros,
@@ -26,7 +29,18 @@ if not PYPY and not os.environ.get("MSGPACK_PUREPYTHON"):
     )
 del libraries, macros
 
+compiler_directives = {
+    "cdivision": True,
+    "embedsignature": True,
+    "boundscheck": False,
+    "wraparound": False,
+}
+
+
+if Version(cython_version) >= Version("3.1.0a0"):
+    compiler_directives["freethreading_compatible"] = True
+
 setup(
-    ext_modules=ext_modules,
+    ext_modules=cythonize(ext_modules, compiler_directives = compiler_directives),
     packages=["msgpack"],
-)
+)
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