diff --git a/Dockerfile b/Dockerfile
index d0ece9f..f363011 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -2,6 +2,8 @@ FROM ubuntu:16.04
 
 ENV DEBIAN_FRONTEND="noninteractive" \
     TERM="xterm"
+ 
+ARG S6_OVERLAY_VERSION=v1.17.2.0
 
 ENTRYPOINT ["/init"]
 
@@ -16,7 +18,7 @@ RUN \
     && \
 
 # Fetch and extract S6 overlay
-    curl -J -L -o /tmp/s6-overlay-amd64.tar.gz https://github.com/just-containers/s6-overlay/releases/download/v1.17.2.0/s6-overlay-amd64.tar.gz && \
+    curl -J -L -o /tmp/s6-overlay-amd64.tar.gz https://github.com/just-containers/s6-overlay/releases/download/${S6_OVERLAY_VERSION}/s6-overlay-amd64.tar.gz && \
     tar xzf /tmp/s6-overlay-amd64.tar.gz -C / && \
 
 # Add user