diff --git a/src/hashtab.c b/src/hashtab.c
index dc0cbb6..482d830 100644
--- a/src/hashtab.c
+++ b/src/hashtab.c
@@ -288,6 +288,7 @@
     ++ht->ht_locked;
 }
 
+#if defined(FEAT_PROP_POPUP) || defined(PROTO)
 /*
  * Lock a hashtable at the specified number of entries.
  * Caller must make sure no more than "size" entries will be added.
@@ -299,6 +300,7 @@
     (void)hash_may_resize(ht, size);
     ++ht->ht_locked;
 }
+#endif
 
 /*
  * Unlock a hashtable: allow ht_array changes again.