diff --git a/plugins/bash/Dockerfile b/plugins/bash/Dockerfile
index 9a6b0ea..6e30b8d 100644
--- a/plugins/bash/Dockerfile
+++ b/plugins/bash/Dockerfile
@@ -1,4 +1,4 @@
-FROM alpine
+FROM alpine@sha256:7144f7bab3d4c2648d7e59409f15ec52a18006a128c733fcff20d3a4a54ba44a
 
 RUN apk add --update --no-cache bash ca-certificates curl
 
diff --git a/plugins/go/Dockerfile b/plugins/go/Dockerfile
index 920640b..21f1f15 100644
--- a/plugins/go/Dockerfile
+++ b/plugins/go/Dockerfile
@@ -1,4 +1,4 @@
-FROM golang:alpine
+FROM golang:alpine@sha256:b255d9352ff4967f0424731acf5a262c3bb4b5bd712e6324ad9ed533c9d2aee7
 
 RUN apk add --update --no-cache ca-certificates
 
diff --git a/plugins/node.js/Dockerfile b/plugins/node.js/Dockerfile
index 7fb13a1..dc89c82 100644
--- a/plugins/node.js/Dockerfile
+++ b/plugins/node.js/Dockerfile
@@ -1,4 +1,4 @@
-FROM node:alpine
+FROM node:alpine@sha256:4721df121cbfd0fa022ac9971ddc9e0bb1ea9abb9faa8fcac6cc1fe8cbd0246b
 
 RUN apk add --update --no-cache ca-certificates
 
diff --git a/plugins/python/Dockerfile b/plugins/python/Dockerfile
index a05dc73..71aefa4 100644
--- a/plugins/python/Dockerfile
+++ b/plugins/python/Dockerfile
@@ -1,4 +1,4 @@
-FROM python:alpine
+FROM python:alpine@sha256:bd16cc548687f25bf7cbc29c3d284c290cf63899b281f0f3a52fc697b48884c7
 
 RUN apk add --update --no-cache ca-certificates
 
diff --git a/plugins/ruby/Dockerfile b/plugins/ruby/Dockerfile
index 69ff5a8..c05c608 100644
--- a/plugins/ruby/Dockerfile
+++ b/plugins/ruby/Dockerfile
@@ -1,4 +1,4 @@
-FROM ruby:alpine
+FROM ruby:alpine@sha256:2689717977dd07ddc14b943b821f15662ee1005b087d61ab932d1a85f3fb01d5
 
 RUN apk add --update --no-cache ca-certificates