diff --git a/docs/features/build_from_dockerfile.md b/docs/features/build_from_dockerfile.md
index dd2628dfc8..19ad060d2e 100644
--- a/docs/features/build_from_dockerfile.md
+++ b/docs/features/build_from_dockerfile.md
@@ -17,7 +17,7 @@ image will be built with a random name and tag.
 If your Dockerfile expects build args: 
 
 ```Dockerfile
-FROM alpine
+FROM alpine@sha256:51b67269f354137895d43f3b3d810bfacd3945438e94dc5ac55fdac340352f48
 
 ARG FOO
 
diff --git a/modules/redis/testdata/Dockerfile b/modules/redis/testdata/Dockerfile
index bf302c6240..7157611a13 100644
--- a/modules/redis/testdata/Dockerfile
+++ b/modules/redis/testdata/Dockerfile
@@ -1 +1 @@
-FROM docker.io/redis:5.0-alpine
\ No newline at end of file
+FROM docker.io/redis:5.0-alpine@sha256:1a3c609295332f1ce603948142a132656c92a08149d7096e203058533c415b8c
diff --git a/testdata/Dockerfile b/testdata/Dockerfile
index bf302c6240..7157611a13 100644
--- a/testdata/Dockerfile
+++ b/testdata/Dockerfile
@@ -1 +1 @@
-FROM docker.io/redis:5.0-alpine
\ No newline at end of file
+FROM docker.io/redis:5.0-alpine@sha256:1a3c609295332f1ce603948142a132656c92a08149d7096e203058533c415b8c
diff --git a/wait/testdata/Dockerfile b/wait/testdata/Dockerfile
index 512f09c8fc..ad92401796 100644
--- a/wait/testdata/Dockerfile
+++ b/wait/testdata/Dockerfile
@@ -1,4 +1,4 @@
-FROM golang:1.18-alpine as builder
+FROM golang:1.18-alpine@sha256:77f25981bd57e60a510165f3be89c901aec90453fd0f1c5a45691f6cb1528807 as builder
 WORKDIR /app
 COPY . .
 RUN mkdir -p dist