diff --git a/.gn b/.gn
index b62075d35..0479a7a7f 100644
--- a/.gn
+++ b/.gn
@@ -35,4 +35,6 @@ exec_script_allowlist = build_dotfile_settings.exec_script_allowlist +
 default_args = {
   mac_sdk_min = "10.12"
   ios_deployment_target = "12.0"
+  # Use Siso instead of Ninja.
+  use_siso = true
 }