diff --git a/Dockerfile b/Dockerfile
index 5ec9d45..304abf6 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -2,10 +2,10 @@
 #
 # SPDX-License-Identifier: AGPL-3.0-or-later
 
-FROM python:3.8.18-alpine as builder
+FROM python:3.8.18-alpine AS builder
 
-ENV PYROOT /pyroot
-ENV PYTHONUSERBASE $PYROOT
+ENV PYROOT=/pyroot
+ENV PYTHONUSERBASE=$PYROOT
 
 RUN apk add --no-cache \
     gcc \
@@ -20,10 +20,10 @@ RUN PIP_USER=1 PIP_IGNORE_INSTALLED=1 pipenv install --system --deploy --ignore-
 RUN pip3 uninstall --yes pipenv
 
 
-FROM python:3.8.18-alpine as ki-backend
+FROM python:3.8.18-alpine AS ki-backend
 
-ENV PYROOT /pyroot
-ENV PYTHONUSERBASE $PYROOT
+ENV PYROOT=/pyroot
+ENV PYTHONUSERBASE=$PYROOT
 
 # Install six explicitly. Otherwise Python complains about it missing.
 RUN pip3 install six