diff --git a/examples/helloworld-service-opt-4/Dockerfile b/examples/helloworld-service-opt-4/Dockerfile
index 125391e..9ade23d 100644
--- a/examples/helloworld-service-opt-4/Dockerfile
+++ b/examples/helloworld-service-opt-4/Dockerfile
@@ -1,4 +1,4 @@
-FROM java:8
+FROM java:8@sha256:c1ff613e8ba25833d2e1940da0940c3824f03f802c449f3d1815a66b7f8c0e9d
 ENTRYPOINT ["java", "-jar", "/app/app.jar"]
 
 COPY maven/target/helloworld-service-0.1-opt-4.jar /app/app.jar