diff --git a/luamml-patches-kernel.sty b/luamml-patches-kernel.sty
index e03a991..1c1540d 100644
--- a/luamml-patches-kernel.sty
+++ b/luamml-patches-kernel.sty
@@ -2,7 +2,7 @@
   {Feel free to add a description here}
 
 \cs_new:Npn \__luamml_kernel_phantom:nnn #1#2#3 {
-  \hbox_set:Nn \c_zero_int {
+  \setbox \z@ = \hbox {
     $
     \m@th
     #2