diff --git a/chunkedstorage.cc b/chunkedstorage.cc
index 26e32cde..54a7c13c 100644
--- a/chunkedstorage.cc
+++ b/chunkedstorage.cc
@@ -137,7 +137,7 @@ char * Reader::getBlock( uint32_t address, vector< char > & chunk )
   // Read and decompress the chunk
   {
     // file.seek( offsets[ chunkIdx ] );
-    Mutex::Lock _( file.lock );
+    QMutexLocker _( &file.lock );
     auto bytes = file.map( offsets[ chunkIdx ], 8 );
     if( bytes == nullptr )
       throw mapFailed();
diff --git a/file.hh b/file.hh
index a69f3840..fa819306 100644
--- a/file.hh
+++ b/file.hh
@@ -45,7 +45,7 @@ class Class
   void open( char const * filename, char const * mode ) ;
 
 public:
-  Mutex lock;
+  QMutex lock;
 
   Class( char const * filename, char const * mode ) ;