diff --git a/lib/bsd/capsicum/ffi.rb b/lib/bsd/capsicum/ffi.rb
index 9066acb..b9fd324 100644
--- a/lib/bsd/capsicum/ffi.rb
+++ b/lib/bsd/capsicum/ffi.rb
@@ -64,4 +64,5 @@ module BSD::Capsicum
       @libc ||= Fiddle.dlopen Dir["/lib/libc.*"].first
     end
   end
+  private_constant :FFI
 end