diff --git a/ui/build/config.go b/ui/build/config.go
index 840f505..5a6d5db 100644
--- a/ui/build/config.go
+++ b/ui/build/config.go
@@ -143,6 +143,9 @@
 		"ANDROID_DEV_SCRIPTS",
 		"ANDROID_EMULATOR_PREBUILTS",
 		"ANDROID_PRE_BUILD_PATHS",
+
+		// Only set in multiproduct_kati after config generation
+		"EMPTY_NINJA_FILE",
 	)
 
 	// Tell python not to spam the source tree with .pyc files.
diff --git a/ui/build/kati.go b/ui/build/kati.go
index 56e9a88..d2e9fe9 100644
--- a/ui/build/kati.go
+++ b/ui/build/kati.go
@@ -81,6 +81,10 @@
 		"--kati_stats",
 	}, args...)
 
+	if config.Environment().IsEnvTrue("EMPTY_NINJA_FILE") {
+		args = append(args, "--empty_ninja_file")
+	}
+
 	cmd := Command(ctx, config, "ckati", executable, args...)
 	cmd.Sandbox = katiSandbox
 	pipe, err := cmd.StdoutPipe()