diff --git a/Dockerfile b/Dockerfile
index 360d90d..6fb06b5 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -22,10 +22,12 @@
 COPY init.groovy /usr/share/jenkins/ref/init.groovy.d/tcp-slave-agent-port.groovy
 
 ENV JENKINS_VERSION 1.596.2
+ENV JENKINS_SHA 96ee85602a41d68c164fb54d4796be5d1d9cc5d0
 
 # could use ADD but this one does not check Last-Modified header 
 # see https://github.com/docker/docker/issues/8331
-RUN curl -L http://mirrors.jenkins-ci.org/war-stable/$JENKINS_VERSION/jenkins.war -o /usr/share/jenkins/jenkins.war
+RUN curl -L http://mirrors.jenkins-ci.org/war-stable/$JENKINS_VERSION/jenkins.war -o /usr/share/jenkins/jenkins.war \
+  && echo "$JENKINS_SHA /usr/share/jenkins/jenkins.war" | sha1sum -c -
 
 ENV JENKINS_UC https://updates.jenkins-ci.org
 RUN chown -R jenkins "$JENKINS_HOME" /usr/share/jenkins/ref