diff --git a/ui/build/kati.go b/ui/build/kati.go
index 06ec646..dad68fa 100644
--- a/ui/build/kati.go
+++ b/ui/build/kati.go
@@ -136,7 +136,7 @@
 	// information out with --empty_ninja_file.
 	//
 	// From https://github.com/google/kati/commit/87b8da7af2c8bea28b1d8ab17679453d859f96e5
-	if config.Environment().IsEnvTrue("EMPTY_NINJA_FILE") {
+	if config.EmptyNinjaFile() {
 		args = append(args, "--empty_ninja_file")
 	}