<?php
// Allow SVG
add_filter( 'wp_check_filetype_and_ext', function($data, $file, $filename, $mimes) {

  global $wp_version;
  if ( $wp_version !== '4.7.1' ) {
     return $data;
  }

  $filetype = wp_check_filetype( $filename, $mimes );

  return [
      'ext'             => $filetype['ext'],
      'type'            => $filetype['type'],
      'proper_filename' => $data['proper_filename']
  ];

}, 10, 4 );