diff --git a/src/proto/list.pro b/src/proto/list.pro
index 2699050..b77add5 100644
--- a/src/proto/list.pro
+++ b/src/proto/list.pro
@@ -52,6 +52,7 @@
 void f_add(typval_T *argvars, typval_T *rettv);
 void f_count(typval_T *argvars, typval_T *rettv);
 void f_extend(typval_T *argvars, typval_T *rettv);
+void f_extendnew(typval_T *argvars, typval_T *rettv);
 void f_insert(typval_T *argvars, typval_T *rettv);
 void f_remove(typval_T *argvars, typval_T *rettv);
 void f_reverse(typval_T *argvars, typval_T *rettv);