diff --git a/pyproject.toml b/pyproject.toml
new file mode 100644
index 0000000..3b109da
--- /dev/null
+++ b/pyproject.toml
@@ -0,0 +1,2 @@
+[build-system]
+requires = ["setuptools", "cython>=0.28.4,<4"]
diff --git a/setup.py b/setup.py
index 35a4a4b..37d1cde 100644
--- a/setup.py
+++ b/setup.py
@@ -31,7 +31,6 @@
     pass
 
 dev_requires = [
-    "cython>=0.28.4",
     "flake8>=2.5",
     "pytest>=2.8",
     "sphinx-rtd-theme>=0.1.9",
@@ -40,13 +39,6 @@
 ] + tornado_requires
 
 
-# cython detection
-try:
-    from Cython.Build import cythonize
-    CYTHON = True
-except ImportError:
-    CYTHON = False
-
 cmdclass = {}
 ext_modules = []
 
@@ -56,11 +48,10 @@
 
 # only build ext in CPython with UNIX platform
 if UNIX and not PYPY:
-    # rebuild .c files if cython available
-    if CYTHON:
-        cythonize("thriftpy2/transport/cybase.pyx")
-        cythonize("thriftpy2/transport/**/*.pyx")
-        cythonize("thriftpy2/protocol/cybin/cybin.pyx")
+    from Cython.Build import cythonize
+    cythonize("thriftpy2/transport/cybase.pyx")
+    cythonize("thriftpy2/transport/**/*.pyx")
+    cythonize("thriftpy2/protocol/cybin/cybin.pyx")
 
     ext_modules.append(Extension("thriftpy2.transport.cybase",
                                  ["thriftpy2/transport/cybase.c"]))