diff --git a/dockerfiles/pixiecore/Dockerfile b/dockerfiles/pixiecore/Dockerfile
index 3006b54..1de9d58 100644
--- a/dockerfiles/pixiecore/Dockerfile
+++ b/dockerfiles/pixiecore/Dockerfile
@@ -2,8 +2,8 @@ FROM alpine:3.6
 
 MAINTAINER David Anderson <dave@natulte.net>
 
-ENV PIXIECORE_SANDBOX /tmp/sandbox
-ENV PIXIECORE_CONTEXT "$PIXIECORE_SANDBOX"/context
+ARG PIXIECORE_SANDBOX=/tmp/sandbox
+ARG PIXIECORE_CONTEXT="$PIXIECORE_SANDBOX"/context
 
 COPY . "$PIXIECORE_CONTEXT"