diff --git a/ext/hbsdctl.rb/hbsdctl.c b/ext/hbsdctl.rb/hbsdctl.c
index c97bdd9..c39faa6 100644
--- a/ext/hbsdctl.rb/hbsdctl.c
+++ b/ext/hbsdctl.rb/hbsdctl.c
@@ -69,9 +69,9 @@ Init_hbsdctl(void)
         rb_cFeature = rb_const_get(rb_mControl, rb_intern("Feature")),
         rb_mFFI     = rb_const_get(rb_mControl, rb_intern("FFI"));
 
-  rb_define_const(rb_mControl, "SysDef", -1);
-  rb_define_const(rb_mControl, "Disable", 0);
-  rb_define_const(rb_mControl, "Enable", 1);
+  rb_define_const(rb_mControl, "SysDef", INT2NUM(-1));
+  rb_define_const(rb_mControl, "Disable", INT2NUM(0));
+  rb_define_const(rb_mControl, "Enable", INT2NUM(1));
   rb_define_singleton_method(rb_mFFI, "available_features", ffi_available_features, 0);
   rb_define_singleton_method(rb_mFFI, "library_version", ffi_library_version, 0);
   rb_define_method(rb_cFeature, "set!", feature_set, 2);