How to use pthread on Qt Creator

I want to execute a following code.

#include <iostream>
#include <thread>

void output() {
    std::cout << "Hello World" << std::endl;
}

int main()
{
    std::thread t(output);
    t.join();

    return 0;
}

I can't execute it.

Qt Creator outputs terminate called after throwing an instance of 'std::system_error' what(): Operation not permitted

However I can execute on the terminal using the option of -pthread. Could you tell me how to use the option of -pthread in Qt Creator?

My developing environment is Ubuntu(12.04), g++4.6.3, Qt Creator(2.4.1).

Thank you.