diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 2b29fa3..91bff92 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -17,7 +17,7 @@ jobs:
       fail-fast: false
       matrix:
         os: [ubuntu-latest, macos-latest]
-        python-version: ["3.8", "3.9", "3.10", "3.11", "3.12"]
+        python-version: ["3.8", "3.9", "3.10", "3.11", "3.12", "3.13"]
     steps:
     - uses: actions/checkout@v4
       with:
diff --git a/pyopa/backend/pyopa.pyx b/pyopa/backend/pyopa.pyx
index 0ccb6f2..3fbed04 100644
--- a/pyopa/backend/pyopa.pyx
+++ b/pyopa/backend/pyopa.pyx
@@ -1,18 +1,20 @@
+# cython: language_level=3
+
 import json
-import logging
 import math
 import os
-import pkgutil
 import re
 import sys
 from math import log10
-from subprocess import call
 
-cimport cpyopa
+from . cimport cpyopa
 cimport numpy as np
 import numpy as np
 
 
+
+
+
 def matrix_dir():
     default_matrix_dir = os.path.realpath(
         os.path.join(os.path.dirname(__file__), '..', 'matrices', 'json'))
diff --git a/pyproject.toml b/pyproject.toml
index 539b599..c079aeb 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -3,6 +3,6 @@ requires = [
     # setuptools, wheel and Cython are needed for the setup.py based build
     "setuptools>=59.2.0",
     "wheel>=0.37.0",
-    "Cython>=0.29.30,<3.0",
+    "Cython>=3.0",
     "numpy",
 ]
diff --git a/setup.py b/setup.py
index a20b059..6d23368 100644
--- a/setup.py
+++ b/setup.py
@@ -26,8 +26,9 @@
             sources=[os.path.join(package_name, 'backend', 'pyopa.pyx')] +
                     list(map(lambda c: os.path.join(c_dir, c), c_sources)),
             extra_compile_args=['-O2', '-DSIMDE_ENABLE_NATIVE_ALIASES'], #, '-DPY_DEBUG'],
-            include_dirs=[c_dir, numpy.get_include(), '.']
-        )]
+            include_dirs=[c_dir, os.path.join(package_name, "backend"), numpy.get_include(), '.']
+        )],
+        compiler_directives={"language_level": "3"},
     ),
     name=package_name,
     version=__version__,