diff --git a/producer/api/include/producer/common.h b/producer/api/include/producer/common.h
index 90b8a954b6647c1c7013c6aabf75f8c32139e222..e8c0d8522f2e64f82a790ae77811a6581f75e613 100644
--- a/producer/api/include/producer/common.h
+++ b/producer/api/include/producer/common.h
@@ -21,7 +21,7 @@ enum class RequestHandlerType {
 
 struct EventHeader {
     uint64_t file_id;
-    size_t file_size;
+    uint64_t file_size;
     std::string file_name;
 };
 
diff --git a/producer/api/src/producer_impl.cpp b/producer/api/src/producer_impl.cpp
index 7c53a0bf735528e83cfe3cea3850774223317ab9..c7e4c26f3b0b6195bc5cd9d067cf69239f4b921d 100644
--- a/producer/api/src/producer_impl.cpp
+++ b/producer/api/src/producer_impl.cpp
@@ -27,7 +27,7 @@ ProducerImpl::ProducerImpl(std::string endpoint, uint8_t n_processing_threads, a
     request_pool__.reset(new RequestPool{n_processing_threads, request_handler_factory_.get()});
 }
 
-GenericRequestHeader ProducerImpl::GenerateNextSendRequest(uint64_t file_id, size_t file_size, std::string file_name) {
+GenericRequestHeader ProducerImpl::GenerateNextSendRequest(uint64_t file_id, uint64_t file_size, std::string file_name) {
     GenericRequestHeader request{kOpcodeTransferData, file_id, file_size, std::move(file_name)};
     return request;
 }
diff --git a/producer/api/src/producer_impl.h b/producer/api/src/producer_impl.h
index f2359052ec0d580e6924498f66b688b468dca509..55d6e7bbbb72d04badbf3622d00db1024f58fc0c 100644
--- a/producer/api/src/producer_impl.h
+++ b/producer/api/src/producer_impl.h
@@ -34,7 +34,7 @@ class ProducerImpl : public Producer {
     Error SetBeamtimeId(std::string beamtime_id) override;
 
   private:
-    GenericRequestHeader GenerateNextSendRequest(uint64_t file_id, size_t file_size, std::string file_name);
+    GenericRequestHeader GenerateNextSendRequest(uint64_t file_id, uint64_t file_size, std::string file_name);
     std::string beamtime_id_;
 };
 
diff --git a/producer/event_monitor_producer/src/system_folder_watch_windows.h b/producer/event_monitor_producer/src/system_folder_watch_windows.h
index 61ce57d5d441bdff9caaa8b6819bddc00c3d58f1..cf55b0e2700e7e560008c0bc900ade8a10504a96 100644
--- a/producer/event_monitor_producer/src/system_folder_watch_windows.h
+++ b/producer/event_monitor_producer/src/system_folder_watch_windows.h
@@ -13,8 +13,9 @@
 namespace asapo {
 
 class SystemFolderWatch {
-  Error StartFolderMonitor(const std::vector<std::string>& monitored_folders);
-  FileEvents GetFileEventList(Error* err);
+ public:
+  VIRTUAL Error StartFolderMonitor(const std::vector<std::string>& monitored_folders);
+  VIRTUAL FileEvents GetFileEventList(Error* err);
 
 };