diff --git a/pyproject.toml b/pyproject.toml
index f2e7d3e..8e5ccc2 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -2,8 +2,7 @@
 requires = [
      # pin NumPy version used in the build
      "oldest-supported-numpy",
-     "setuptools>=43.0.0",
-     "Cython>=0.29.23"
+     "setuptools>=43.0.0"
 ]
 build-backend = "setuptools.build_meta"