diff --git a/source.list b/source.list
--- a/source.list
+++ b/source.list
@@ -441,6 +441,7 @@ rail_cmd.cpp
 road_cmd.cpp
 roadveh_cmd.cpp
 ship_cmd.cpp
+signs_cmd.cpp
 station_cmd.cpp
 terraform_cmd.cpp
 timetable_cmd.cpp