diff --git a/setup.cfg b/setup.cfg
index 925043b..5219ec7 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -30,6 +30,7 @@ python_requires = >=3.6
 install_requires =
     wheel==0.36.2
     build==0.1.0
+    pep517==0.9.1
     packaging==20.8
     toml==0.10.2
     twine==3.3.0