diff --git a/economy.c b/economy.c
--- a/economy.c
+++ b/economy.c
@@ -1,5 +1,6 @@
 #include "stdafx.h"
 #include "openttd.h"
+#include "functions.h"
 #include "strings.h" // XXX InjectDParam()
 #include "table/strings.h"
 #include "map.h"