diff --git a/src/openttd.h b/src/openttd.h
--- a/src/openttd.h
+++ b/src/openttd.h
@@ -67,6 +67,7 @@ typedef uint16 SignID;
 typedef uint16 GroupID;
 typedef uint16 EngineRenewID;
 typedef uint16 DestinationID;
+typedef int32 CommandCost;
 
 /* DestinationID must be at least as large as every these below, because it can
  * be any of them