diff --git a/w32dm.c b/w32dm.c
index 2c60768a27..782fed2161 100644
--- a/w32dm.c
+++ b/w32dm.c
@@ -30,6 +30,7 @@
 
 #include "openttd.h"
 #include "string.h"
+#include "variables.h"
 #include "sound.h"
 #include "hal.h"