PVS-Studio warning V512 for Fennec Media Project

#define uinput_size       1024
typedef wchar_t letter;

letter  uinput_text[uinput_size];

string basewindows_getuserinput(const string title,
  const string cap, const string dtxt)
{
  memset(uinput_text, 0, uinput_size);
  ...
}

At the first sight, everything is fine with "memset(uinput_text, 0, uinput_size);". Perhaps it even was fine when the 'letter' type was 'char'. But now this is 'wchar_t', which results in zeroing only half of the buffer.

This suspicious code was found in Fennec Media Project project by PVS-Studio static code analyzer.
Warning message is:
V512 A call of the 'memset' function will lead to a buffer overflow or underflow. base windows.c 150

PVS-Studio is a static analyzer for detecting bugs in the source code of applications written in C, C++, C++11, C++/CX. Site: http://www.viva64.com/en/pvs-studio/