diff --git a/versions.cfg b/versions.cfg
index 90ae813..d85b74c 100644
--- a/versions.cfg
+++ b/versions.cfg
@@ -7,3 +7,4 @@ traitlets = 4.3.2
 python-dateutil = 2.8.0
 # html.escape backport is not available in old future...
 future = 0.18.2
+pep517 = 0.12.0