diff --git a/Earthfile b/Earthfile
index bd1058a..7544c00 100644
--- a/Earthfile
+++ b/Earthfile
@@ -1,5 +1,10 @@
 VERSION 0.8
 
+ctx:
+    FROM busybox
+    RUN mkdir -p /tmp/docker-build
+    SAVE ARTIFACT /tmp/docker-build
+
 xwin:
-    FROM DOCKERFILE -f xwin.dockerfile /tmp/docker-build
+    FROM DOCKERFILE -f xwin.dockerfile +ctx/docker-build
     SAVE IMAGE xwin:latest