diff --git a/setup.py b/setup.py
index 68e663b..4dca651 100755
--- a/setup.py
+++ b/setup.py
@@ -88,7 +88,7 @@
     version=VERSION,
     description='Library for handling efficiently sorted integer sets.',
     long_description=long_description,
-    setup_requires=['cython>=3.0.2'],
+    setup_requires=['cython>=3.0.2,<3.1.0'],
     url='https://github.com/Ezibenroc/PyRoaringBitMap',
     author='Tom Cornebize',
     author_email='tom.cornebize@gmail.com',
diff --git a/tox.ini b/tox.ini
index f4def40..93632e0 100644
--- a/tox.ini
+++ b/tox.ini
@@ -13,7 +13,7 @@ setenv =
 deps =
 	hypothesis
     pytest
-	cython>=3.0.2
+	cython>=3.0.2,<3.1.0
 passenv =
 	HYPOTHESIS_PROFILE
 	ROARING_BITSIZE