diff --git a/1.7/Dockerfile b/1.7/Dockerfile
index 72900bb..fd940ce 100644
--- a/1.7/Dockerfile
+++ b/1.7/Dockerfile
@@ -1,4 +1,4 @@
-FROM php:7.4.14-fpm-buster
+FROM php:7.4.14-fpm-buster@sha256:c1f7ffbe18bbde526c883284d6f02fd26ff11717c1b4e4e9e8815ea177768315
 
 SHELL [ "/bin/bash", "-c" ]