Found a solution.
Edit > class-sidebar-login-widget
if ( $show_avatar == 1 ) {
echo '<div class="avatar_container"><a href="' . get_author_posts_url($this->user->ID) . '">' . get_avatar( $this->user->ID, apply_filters( 'sidebar_login_widget_avatar_size', 40 ) ) . '</a></div>';
}