--- a/ship_cmd.c	Mon Jan 16 15:23:06 2006 +0000
+++ b/ship_cmd.c	Wed Jan 18 14:12:26 2006 +0000
@@ -827,7 +827,7 @@
 	TileIndex tile = TileVirtXY(x, y);
 	Engine *e;
 
-	if (!IsEngineBuildable(p1, VEH_Ship)) return CMD_ERROR;
+	if (!IsEngineBuildable(p1, VEH_Ship)) return_cmd_error(STR_ENGINE_NOT_BUILDABLE);
 
 	SET_EXPENSES_TYPE(EXPENSES_NEW_VEHICLES);