diff --git a/ui/build/ninja.go b/ui/build/ninja.go
index dfc3be1..1b13e5d 100644
--- a/ui/build/ninja.go
+++ b/ui/build/ninja.go
@@ -58,6 +58,7 @@
 	args = append(args, "-f", config.CombinedNinjaFile())
 
 	args = append(args,
+		"-o", "usesphonyoutputs=yes",
 		"-w", "dupbuild=err",
 		"-w", "missingdepfile=err")