diff --git a/calculate_parking_tickets/calculate_parking_tickets_global.h b/calculate_parking_tickets/calculate_parking_tickets_global.h
index 2dc2ecd..61e420c 100644
--- a/calculate_parking_tickets/calculate_parking_tickets_global.h
+++ b/calculate_parking_tickets/calculate_parking_tickets_global.h
@@ -20,6 +20,7 @@ typedef struct price_t {
     double brutto;
     double vat_percentage;
     double vat;
+    bool valid;
 } price_t;
 
 static constexpr uint16_t const MIN_PER_DAY = 1440;