diff --git a/Dockerfile b/Dockerfile
index 65aeb525886e26f8db6a75fcb4936cd89de4fcfa..5f2e6656047761e05e1eb89db3ce7eb83de1c96c 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,17 +1,17 @@
-ARG ALPINE_VERSION
-ARG PHP_MAJOR_VERSION
+ARG ALPINE_VERSION=undefined
+ARG PHP_MAJOR_VERSION=undefined
 
 FROM php:${PHP_MAJOR_VERSION}-cli-alpine${ALPINE_VERSION}
 
-ARG VERSION
+ARG VERSION=undefined
 
 LABEL com.example.vendor="LakeDrops" \
       maintainer="juergen.haas@lakedrops.com" \
       version="${VERSION}" \
       description="An image for GitLab runner to build and test Drupal projects."
 
-ARG ALPINE_VERSION
-ARG PHP_MAJOR_VERSION
+ARG ALPINE_VERSION=undefined
+ARG PHP_MAJOR_VERSION=undefined
 ARG AHOY_VERSION=2.2.0
 ARG DIFFTASTIC_VERSION=0.60.0
 ARG DOCKER_CHANNEL=stable
@@ -19,12 +19,12 @@ ARG DOCKER_CHANNEL=stable
 ARG DOCKER_VERSION=27.3.1
 ARG GIT_EXTRAS_VERSION=7.2.0
 ARG GLAB_VERSION=1.48.0
-ARG apkArch
+ARG APK_ARCH=undefined
 ARG buildx_version=0.17.1
 # IMPORTANT: keep the docker compose version in sync with the Ansible Docker role.
 ARG compose_version=2.29.7
 ARG composer_version=2.8.1
-ARG dockerArch
+ARG DOCKER_ARCH=undefined
 ARG fx_version=35.0.0
 ARG glibc_version=2.35-r1
 ARG yq_version=4.44.3
@@ -36,20 +36,20 @@ ADD etc/* /etc/
 RUN echo 'hosts: files dns' > /etc/nsswitch.conf && \
     set -eux && \
     \
-    apkArch="$(apk --print-arch)" && \
-    case "$apkArch" in \
-      x86_64) dockerArch='x86_64' ;; \
-      armhf) dockerArch='armel' ;; \
-      aarch64) dockerArch='aarch64' ;; \
-      ppc64le) dockerArch='ppc64le' ;; \
-      s390x) dockerArch='s390x' ;; \
-      *) echo >&2 "error: unsupported architecture ($apkArch)"; exit 1 ;;\
+    APK_ARCH="$(apk --print-arch)" && \
+    case "$APK_ARCH" in \
+      x86_64) DOCKER_ARCH='x86_64' ;; \
+      armhf) DOCKER_ARCH='armel' ;; \
+      aarch64) DOCKER_ARCH='aarch64' ;; \
+      ppc64le) DOCKER_ARCH='ppc64le' ;; \
+      s390x) DOCKER_ARCH='s390x' ;; \
+      *) echo >&2 "error: unsupported architecture ($APK_ARCH)"; exit 1 ;;\
     esac && \
     \
     apk add --no-cache ca-certificates curl openssl && \
     \
-    if ! curl -fSL -o docker.tgz "https://download.docker.com/linux/static/${DOCKER_CHANNEL}/${dockerArch}/docker-${DOCKER_VERSION}.tgz"; then \
-      echo >&2 "error: failed to download 'docker-${DOCKER_VERSION}' from '${DOCKER_CHANNEL}' for '${dockerArch}'"; \
+    if ! curl -fSL -o docker.tgz "https://download.docker.com/linux/static/${DOCKER_CHANNEL}/${DOCKER_ARCH}/docker-${DOCKER_VERSION}.tgz"; then \
+      echo >&2 "error: failed to download 'docker-${DOCKER_VERSION}' from '${DOCKER_CHANNEL}' for '${DOCKER_ARCH}'"; \
       exit 1; \
     fi && \
     \
@@ -100,9 +100,9 @@ RUN echo 'hosts: files dns' > /etc/nsswitch.conf && \
     pip install python-gitlab && \
     pip install visidata && \
     \
-    wget -q https://gitlab.com/gitlab-org/cli/-/releases/v${GLAB_VERSION}/downloads/glab_${GLAB_VERSION}_Linux_x86_64.apk && \
-    apk add --no-cache --allow-untrusted glab_${GLAB_VERSION}_Linux_x86_64.apk && \
-    rm glab_${GLAB_VERSION}_Linux_x86_64.apk && \
+    wget -q https://gitlab.com/gitlab-org/cli/-/releases/v${GLAB_VERSION}/downloads/glab_${GLAB_VERSION}_linux_amd64.apk && \
+    apk add --no-cache --allow-untrusted glab_${GLAB_VERSION}_linux_amd64.apk && \
+    rm glab_${GLAB_VERSION}_linux_amd64.apk && \
     \
     wget -q https://github.com/Wilfred/difftastic/releases/download/${DIFFTASTIC_VERSION}/difft-x86_64-unknown-linux-gnu.tar.gz && \
     tar -xf difft-x86_64-unknown-linux-gnu.tar.gz && \