diff --git a/Dockerfile b/Dockerfile
index b39af93..c879c05 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -39,6 +39,6 @@ ENV TFW_SUPERVISORD_CONF="/etc/supervisor/supervisord.conf"
 COPY supervisord.conf ${TFW_SUPERVISORD_CONF}
 
 ENV WEB_PORT=4242
-EXPOSE 4242
+EXPOSE ${WEB_PORT}
 
 CMD . "$HOME/.pyenvrc" && exec supervisord --nodaemon