diff --git a/Dockerfile b/Dockerfile
index beb7f1d..d91bc9b 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -27,8 +27,10 @@
 
 COPY init.groovy /usr/share/jenkins/ref/init.groovy.d/tcp-slave-agent-port.groovy
 
-ENV JENKINS_VERSION 1.642.2
-ENV JENKINS_SHA e72e06e64d23eefb13090459f517b0697aad7be0
+ARG JENKINS_VERSION
+ENV JENKINS_VERSION ${JENKINS_VERSION:-1.642.2}
+ARG JENKINS_SHA
+ENV JENKINS_SHA ${JENKINS_SHA:-e72e06e64d23eefb13090459f517b0697aad7be0}
 
 
 # could use ADD but this one does not check Last-Modified header