diff --git a/Dockerfile b/Dockerfile
index 20ab9f8..ec726e5 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,7 +1,7 @@
-FROM jfloff/alpine-python:2.7
+ARG PUID=1000
+ARG PGID=1000
 
-ENV PUID="${PUID:-1000}"
-ENV PGID="${PGID:-1000}"
+FROM jfloff/alpine-python:2.7
 ENV PYTHONPATH="/usr/local/lib/python2.7/site-packages:/usr/lib/python2.7/site-packages"
 
 WORKDIR /mopidy
@@ -52,7 +52,7 @@ RUN \
       Mopidy-Local-SQLite \
   && echo "* Creating Mopidy User" \
     && addgroup -g ${PGID} mopidy \
-    && adduser -h /mopidy -s /bin/sh -D -G mopidy -u ${PUID} mopidy \
+    && adduser -h /mopidy -s /bin/sh -D -G mopidy -u $PUID mopidy \
     && echo "mopidy ALL=NOPASSWD: /usr/local/lib/pyenv/versions/2.7.16/lib/python2.7/site-packages/mopidy_iris/system.sh" >> /etc/sudoers \
   && echo "* Cleaning up" \
     && rm -rf /var/cache/apk/* \