diff --git a/Dockerfile b/Dockerfile
index a2780d5..935e3fc 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -61,7 +61,7 @@ COPY root /
 # Create a Python virtual environment for use by any application to avoid
 # potential conflicts with Python packages preinstalled in the main Python
 # installation.
-RUN virtualenv-$VERSION /opt/app-root
+RUN virtualenv-$PYTHON_VERSION /opt/app-root
 
 # In order to drop the root user, we have to make some directories world
 # writable as OpenShift default security model is to run the container under