Just need some clarification on Constexpr and Visual Studio 2013

I have the following code (please don't mind the fact that more headers than necessary have been included, the code had more. I wanted to focus more on the issue). Is constexpr not allowed in Visual Studio 2013? I would just like to clarify this because I get an error when using it.

#include <iostream>
#include <string>
#include <vector>
#include <cstddef>


using std::string; using std::cin;
using std::cout; using std::endl;
using std::vector;

int main(){
    constexpr int i = 1;

    system("pause");
}