diff --git a/app1/Dockerfile b/app1/Dockerfile
index 06c09d5..b1243a6 100644
--- a/app1/Dockerfile
+++ b/app1/Dockerfile
@@ -1,4 +1,4 @@
-FROM node:lts-alpine
+FROM node:lts-slim@sha256:86419100dc5376dd492552be338755c9ae20f578a18bfd97d5b351426a772f7f
 
 WORKDIR /opt/project
 
diff --git a/app2/Dockerfile b/app2/Dockerfile
index 61aecdb..ffffd62 100644
--- a/app2/Dockerfile
+++ b/app2/Dockerfile
@@ -1,4 +1,4 @@
-FROM node:lts-slim
+FROM node:lts-slim@sha256:86419100dc5376dd492552be338755c9ae20f578a18bfd97d5b351426a772f7f
 
 RUN apt-get update \
     && apt-get install -y wget gnupg \