diff --git a/src/proto/hashtab.pro b/src/proto/hashtab.pro
index 9690714..21794ed 100644
--- a/src/proto/hashtab.pro
+++ b/src/proto/hashtab.pro
@@ -9,6 +9,7 @@
 int hash_add_item(hashtab_T *ht, hashitem_T *hi, char_u *key, hash_T hash);
 void hash_remove(hashtab_T *ht, hashitem_T *hi);
 void hash_lock(hashtab_T *ht);
+void hash_lock_size(hashtab_T *ht, int size);
 void hash_unlock(hashtab_T *ht);
 hash_T hash_hash(char_u *key);
 /* vim: set ft=c : */