diff --git a/pyproject.toml b/pyproject.toml
index 828b52bb..5f456597 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -2,6 +2,5 @@
 build-backend = 'setuptools.build_meta'
 requires = [
     'setuptools >= 43.0.0',
-    # 'numpy', # required to compile f2py extension
-    'cython', # requred to compile cython extension
+    'numpy',
     ]