diff --git a/nginx-flask-mongo/flask/Dockerfile b/nginx-flask-mongo/flask/Dockerfile
index 1a99ea2..6537568 100755
--- a/nginx-flask-mongo/flask/Dockerfile
+++ b/nginx-flask-mongo/flask/Dockerfile
@@ -1,5 +1,5 @@
 # syntax=docker/dockerfile:1.4
-FROM --platform=$BUILDPLATFORM python:3.10-alpine AS builder
+FROM --platform=$BUILDPLATFORM python:3.10-alpine@sha256:c9d3c11e89887c82efeb4f4fee8771a406cf42f41aebbd23148906d5fe3c1426 AS builder
 
 WORKDIR /src
 COPY requirements.txt /src