Index: trunk/data/validator/deprecated.mapcss
===================================================================
--- trunk/data/validator/deprecated.mapcss	(revision 15815)
+++ trunk/data/validator/deprecated.mapcss	(revision 15828)
@@ -690,8 +690,9 @@
 }
 
-/* see #11330 */
+/* see #11330, #18642 */
 *[/^.$/],
 node[/^..$/],
-way[/^..$/],
+way[/^..$/][route=ferry][!to],
+way[/^..$/][route!=ferry],
 relation[/^..$/][!to] {
   throwWarning: tr("uncommon short key");
@@ -699,4 +700,5 @@
   assertMatch: "relation fo=bar";
   assertMatch: "way to=bar";
+  assertNoMatch: "way to=Zuidschermer;Akersloot route=ferry";
   assertMatch: "node fo=bar";
   assertMatch: "node f=b";