How to set Russian encoding in gulp build-html?

Question

gulp.js

I start to collect 2 html into one, but if there were Russian characters in the included html, then they turn into squares in the output file, but in the main file everything is fine, they remain as they were

gulp.task('build-html' , function(){
    return gulp.src("app/1/**/*.html")
        .pipe(gih({
            'public':"app/1",
            //'version':version,
            //baseDir:'/app/Html-init',			
        }))
        .pipe(gulp.dest("dest"));
});