diff --git a/library/src/calculate_price.cpp b/library/src/calculate_price.cpp
index b21741b..f86c668 100644
--- a/library/src/calculate_price.cpp
+++ b/library/src/calculate_price.cpp
@@ -10,7 +10,7 @@
 
 static Calculator calculator;
 
-int get_zone_nr() {
+int CALCULATE_LIBRARY_API get_zone_nr() {
     QFile zone("/etc/zone_nr");
     if (zone.exists()) {
         QFileInfo finfo(zone);
@@ -23,7 +23,7 @@ int get_zone_nr() {
     return -1;
 }
 
-bool init_tariff(parking_tariff_t **tariff, char const *config_file) {
+bool CALCULATE_LIBRARY_API init_tariff(parking_tariff_t **tariff, char const *config_file) {
     *tariff = new Configuration();
 
     int const zone = get_zone_nr();
@@ -52,11 +52,12 @@ bool init_tariff(parking_tariff_t **tariff, char const *config_file) {
     return false;
 }
 
-void free_tariff(parking_tariff_t *tariff) {
+void CALCULATE_LIBRARY_API free_tariff(parking_tariff_t *tariff) {
     delete tariff;
 }
 
-bool compute_price_for_parking_ticket(parking_tariff_t *tariff,
+bool CALCULATE_LIBRARY_API compute_price_for_parking_ticket(
+                                      parking_tariff_t *tariff,
                                       time_t start_parking_time, // in minutes
                                       time_t end_parking_time,   // in minutes
                                       struct price_t *price) {