diff --git a/pkg/universe.dagger.io/docker/build.cue b/pkg/universe.dagger.io/docker/build.cue
index 1274a5e6..d49b5496 100644
--- a/pkg/universe.dagger.io/docker/build.cue
+++ b/pkg/universe.dagger.io/docker/build.cue
@@ -50,7 +50,7 @@ import (
 	_copy: engine.#Copy & {
 		"input":    input.rootfs
 		"contents": contents
-		source:     source
+		"source":   source
 		"dest":     dest
 	}