C++ RNG example from S.O. prints nonrandom numbers (on my machine)

I've been having trouble generating random integers with the example provided by user @Cubbi on this question. I've set up the program as follows:

rand_test.cpp

#include <iostream>
#include <random>

int main()
{
    std::random_device rd;
    std::mt19937 eng(rd());
    std::uniform_int_distribution<> distr(25, 63);

    for(int n = 0; n < 40; ++n)
        std::cout << distr(eng) << ' ';
}

...and compiled it with g++ rand_test.cpp -std=c++11

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I executed the program four times in the span of about a minute and received the exact same output each time. I then executed it again after researching the issue and beginning this question (10-15 minutes) and again, the same output. Then I recompiled, and the output was the same as before. What's the cause and how do I fix this?

• Compiler: TDM-GCC-64
• OS: Windows 10 Home (64 bit)