MinGW g++: Multiple definition of vsnprintf when using to_string

I just started using MinGW for Windows. When trying to create executable using

g++ a.cpp -o a.exe -std=c++14

for the code below:

#include <string>

using namespace std;

int main()
{
    string x = to_string(123);
    return 0;
}

I'm getting following error:

C:/mingw/bin/../lib/gcc/mingw32/5.3.0/../../../libmingwex.a(vsnprintf.o):(.text+0x0): multiple definition of vsnprintf
C:\Users\..\Local\Temp\cc4sJDvK.o:c:/mingw/include/stdio.h:426: first defined here
collect2.exe: error: ld returned 1 exit status

What is the root cause for this error and how can I make it go away? While I can easily find a replacement for to_string() function I'm not sure what is causing this error to occur in the first place.