diff --git a/joplin/Dockerfile b/joplin/Dockerfile
index ccaaba53a..15d8ccd24 100644
--- a/joplin/Dockerfile
+++ b/joplin/Dockerfile
@@ -28,7 +28,8 @@ RUN \
     ###################
 
 # Copy root filesystem
-USER joplin
+ARG user=joplin
+USER $user
 COPY --chown=$user:$user rootfs /
 RUN chmod +x /run.sh