1 files changed, 2 insertions, 0 deletions
diff --git a/date.h b/date.h
index 37691d24a..488a9dc3a 100644
--- a/date.h
+++ b/date.h
@@ -3,6 +3,8 @@
 #ifndef DATE_H
 #define DATE_H
 
+#include "openttd.h"
+
 /**
  * 1 day is 74 ticks; _date_fract used to be uint16 and incremented by 885. On
  *                    an overflow the new day begun and 65535 / 885 = 74.