Why does _block_type_is_valid crash when using QCameraInfo :: availableCameras?

Win7, VS2013, QT 5.4

#include <QtWidgets\QtWidgets> #include <QtMultimedia\QCameraInfo> #pragma comment(lib, "Qt5Widgets.lib") #pragma comment(lib, "Qt5Multimedia.lib") #pragma comment(lib, "Qt5Core.lib") int main(int argc, char* argv[]) { QApplication app(argc, argv); QList<QCameraInfo> cameras = QCameraInfo::availableCameras(); QDialog dlg; dlg.show(); return app.exec(); } 

The dialog starts and shows, but when it is closed, I get _block_type_is_valid in the debugger. In the console window is empty. If you remove the QList<QCameraInfo> cameras ... - everything is ok. I can not understand what I'm doing wrong :-(

UPD1 : crashes only if the camera is connected.