diff --git a/src/train_cmd.h b/src/train_cmd.h
--- a/src/train_cmd.h
+++ b/src/train_cmd.h
@@ -25,4 +25,6 @@ DEF_CMD_TRAIT(CMD_MOVE_RAIL_VEHICLE,    
 DEF_CMD_TRAIT(CMD_FORCE_TRAIN_PROCEED,     CmdForceTrainProceed,     0, CMDT_VEHICLE_MANAGEMENT)
 DEF_CMD_TRAIT(CMD_REVERSE_TRAIN_DIRECTION, CmdReverseTrainDirection, 0, CMDT_VEHICLE_MANAGEMENT)
 
+CommandCallback CcBuildWagon;
+
 #endif /* TRAIN_CMD_H */