--- a/util.c	Mon Jul 02 00:04:53 2018 +0300
+++ b/util.c	Mon Jul 09 05:59:13 2018 +0300
@@ -402,20 +402,24 @@
 }
 
 
-nn_editbuf_t * nn_editbuf_copy(nn_editbuf_t *src)
+void nn_editbuf_copy_to(nn_editbuf_t *dst, const nn_editbuf_t *src)
+{
+    memcpy(dst->data, src->data, src->size);
+    dst->pos = dst->len = src->len;
+    dst->dirty = TRUE;
+}
+
+
+nn_editbuf_t * nn_editbuf_copy(const nn_editbuf_t *src)
 {
     nn_editbuf_t *res;
 
-    assert(src != NULL);
-
     if (src == NULL) return NULL;
 
     if ((res = nn_editbuf_new(src->size)) == NULL)
         return NULL;
 
-    memcpy(res->data, src->data, src->size);
-    res->pos = res->len = src->len;
-    res->dirty = TRUE;
+    nn_editbuf_copy_to(res, src);
 
     return res;
 }