diff --git a/dart/lib/header.dart b/dart/lib/header.dart
index 99f0fd2..57fe656 100644
--- a/dart/lib/header.dart
+++ b/dart/lib/header.dart
@@ -215,50 +215,64 @@ class SweepstoreWorkerTicket {
 
   // Offset 0 - 4 bytes
   int get identifier {
+    _concurrencyHeader._header._file.lockSync(FileLock.shared, _baseOffset, _baseOffset + 4);
     _concurrencyHeader._header._file.setPositionSync(_baseOffset);
     int id = _concurrencyHeader._header._file.readIntSync(4);
+    _concurrencyHeader._header._file.unlockSync(_baseOffset, _baseOffset + 4);
     return id;
   }
 
   // Offset 4 - 4 bytes
   int get workerHeartbeat {
+    _concurrencyHeader._header._file.lockSync(FileLock.shared, _baseOffset + 4, _baseOffset + 8);
     _concurrencyHeader._header._file.setPositionSync(_baseOffset + 4);
     int heartbeat = _concurrencyHeader._header._file.readIntSync(4);
+    _concurrencyHeader._header._file.unlockSync(_baseOffset + 4, _baseOffset + 8);
     return heartbeat;
   }
 
   // Offset 8 - 1 byte
   SweepstoreTicketState get ticketState {
+    _concurrencyHeader._header._file.lockSync(FileLock.shared, _baseOffset + 8, _baseOffset + 9);
     _concurrencyHeader._header._file.setPositionSync(_baseOffset + 8);
     int stateValue = _concurrencyHeader._header._file.readIntSync(1);
+    _concurrencyHeader._header._file.unlockSync(_baseOffset + 8, _baseOffset + 9);
     return SweepstoreTicketState.values[stateValue];
   }
 
   // Offset 9 - 1 byte
   SweepstoreTicketOperation get ticketOperation {
+    _concurrencyHeader._header._file.lockSync(FileLock.shared, _baseOffset + 9, _baseOffset + 10);
     _concurrencyHeader._header._file.setPositionSync(_baseOffset + 9);
     int operationValue = _concurrencyHeader._header._file.readIntSync(1);
+    _concurrencyHeader._header._file.unlockSync(_baseOffset + 9, _baseOffset + 10);
     return SweepstoreTicketOperation.values[operationValue];
   }
 
   // Offset 10 - 8 bytes
   int get keyHash {
+    _concurrencyHeader._header._file.lockSync(FileLock.shared, _baseOffset + 10, _baseOffset + 18);
     _concurrencyHeader._header._file.setPositionSync(_baseOffset + 10);
     int hash = _concurrencyHeader._header._file.readIntSync(8);
+    _concurrencyHeader._header._file.unlockSync(_baseOffset + 10, _baseOffset + 18);
     return hash;
   }
 
   // Offset 18 - 8 bytes
   SweepstorePointer get writePointer {
+    _concurrencyHeader._header._file.lockSync(FileLock.shared, _baseOffset + 18, _baseOffset + 26);
     _concurrencyHeader._header._file.setPositionSync(_baseOffset + 18);
     int address = _concurrencyHeader._header._file.readIntSync(8);
+    _concurrencyHeader._header._file.unlockSync(_baseOffset + 18, _baseOffset + 26);
     return SweepstorePointer(address);
   }
 
   // Offset 26 - 4 bytes
   int get writeSize {
+    _concurrencyHeader._header._file.lockSync(FileLock.shared, _baseOffset + 26, _baseOffset + 30);
     _concurrencyHeader._header._file.setPositionSync(_baseOffset + 26);
     int size = _concurrencyHeader._header._file.readIntSync(4);
+    _concurrencyHeader._header._file.unlockSync(_baseOffset + 26, _baseOffset + 30);
     return size;
   }