diff --git a/lib/rules/subsystem.js b/lib/rules/subsystem.js
index 611765d..c32533f 100644
--- a/lib/rules/subsystem.js
+++ b/lib/rules/subsystem.js
@@ -46,6 +46,7 @@ const validSubsystems = [
   'dns',
   'domain',
   'events',
+  'ffi',
   'fs',
   'http',
   'http2',