diff --git a/src/undo.c b/src/undo.c
index 1cd8912..8c2783a 100644
--- a/src/undo.c
+++ b/src/undo.c
@@ -3683,7 +3683,7 @@
  * "undofile(name)" function
  */
     void
-f_undofile(typval_T *argvars UNUSED, typval_T *rettv)
+f_undofile(typval_T *argvars, typval_T *rettv)
 {
     if (in_vim9script() && check_for_string_arg(argvars, 0) == FAIL)
 	return;
@@ -3738,7 +3738,7 @@
  * "undotree(expr)" function
  */
     void
-f_undotree(typval_T *argvars UNUSED, typval_T *rettv)
+f_undotree(typval_T *argvars, typval_T *rettv)
 {
     if (in_vim9script() && check_for_opt_buffer_arg(argvars, 0) == FAIL)
 	return;