diff --git a/Dockerfile.alpine b/Dockerfile.alpine
index 9ead118..78f5320 100644
--- a/Dockerfile.alpine
+++ b/Dockerfile.alpine
@@ -1,4 +1,4 @@
-FROM alpine
+FROM alpine:3.15.4
 RUN apk add --update bash build-base git autoconf flex bison linux-headers ncurses-dev readline-dev && rm -rf /var/cache/apk/*
 ADD build.sh /build.sh
 RUN echo "alpine" > /dist
diff --git a/Dockerfile.ubuntu b/Dockerfile.ubuntu
index 63c250c..310dbea 100644
--- a/Dockerfile.ubuntu
+++ b/Dockerfile.ubuntu
@@ -1,4 +1,4 @@
-FROM ubuntu
+FROM ubuntu:jammy
 RUN apt -y update && apt -y dist-upgrade && apt -y install build-essential git autoconf flex bison linux-headers-generic libncurses-dev libreadline-dev && apt -y autoremove --purge && apt -y autoclean && rm -rf /var/cache/apt/archives
 ADD build.sh /build.sh
 RUN echo "ubuntu" > /dist