diff --git a/src/ex_cmds2.c b/src/ex_cmds2.c
index f8d35dc..2da38b7 100644
--- a/src/ex_cmds2.c
+++ b/src/ex_cmds2.c
@@ -3526,7 +3526,7 @@
     {
 	/* directory is not yet in 'runtimepath', add it */
 	p4 = p3 = p2 = p1 = get_past_head(ffname);
-	for (p = p1; *p; mb_ptr_adv(p))
+	for (p = p1; *p; MB_PTR_ADV(p))
 	    if (vim_ispathsep_nocolon(*p))
 	    {
 		p4 = p3; p3 = p2; p2 = p1; p1 = p;