diff --git a/Dockerfile b/Dockerfile
index 0e77c47..b33da2f 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,6 +1,7 @@
 FROM debian:buster
 
 ARG SQUID_VERSION
+ENV ENV_SQUID_VERSION=$SQUID_VERSION
 
 WORKDIR /tmp
 RUN echo "deb-src http://deb.debian.org/debian buster main contrib" >> /etc/apt/sources.list && apt-get update && apt-get --no-install-recommends -y build-dep squid && apt-get --no-install-recommends -y install wget tar xz-utils libssl-dev libssl1.1 winbind \