diff --git a/pyproject.toml b/pyproject.toml
index 0b56773e..226c8469 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -52,7 +52,7 @@ docs = [
 requires = [
     'setuptools>=61.2',
     'setuptools_scm>=6.2',
-    'cython>=0.29.36',
+    'cython>=3.0.0,<3.1.0',
     'numpy',
     'extension-helpers',
 ]