diff --git a/pyproject.toml b/pyproject.toml
index c0bd23d..24413ed 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,7 +1,7 @@
 [build-system]
 requires = [
     "setuptools<v60.0",
-    "cython>=0.28.0",
+    "cython>=0.28.0,<3.0.0",
     "oldest-supported-numpy",
 ]
 build-backend = "setuptools.build_meta"
diff --git a/setup.py b/setup.py
index 336144a..443d9a3 100644
--- a/setup.py
+++ b/setup.py
@@ -277,7 +277,7 @@ def run(self):
     cmdclass=cmdclass,
     install_requires=[
         "numpy >= 1.20.0",
-        "cython >= " + min_cython_ver,
+        "cython >= " + min_cython_ver + ",<3.0.0",
         "six",
         "tqdm",
     ],