diff --git a/Dockerfile b/Dockerfile
index 312ccc315c330353062bd3926740098aff8eef00..7cd9aed46eb2f8919baf0792b4ed6723bddc4997 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,2 +1,4 @@
 FROM python:3
-RUN pip install black
+ENV version=
+
+RUN pip install black$(version)