diff --git a/src/window_type.h b/src/window_type.h
--- a/src/window_type.h
+++ b/src/window_type.h
@@ -103,6 +103,7 @@ enum WindowClass {
 	WC_OSK,
 	WC_WAYPOINT_VIEW,
 	WC_SELECT_STATION,
+	WC_SET_DATE,
 	WC_AI_DEBUG,
 	WC_AI_LIST,
 	WC_AI_SETTINGS,