How to apply excerpt length only on front end?

I have a theme on WordPress theme review queue and I'm using the below code to change excerpt length.

function theme_slug_excerpt_length( $length ) {
    return 50;
}
add_filter( 'excerpt_length', 'theme_slug_excerpt_length', 999 );

Now theme reviewer ask to apply that limit on only front end, which is it should not impact on admin side.

So will this below code work?

function theme_slug_excerpt_length( $length ) {
    if ( is_admin() ) {
        return $length;
    }
    return 50;
}
add_filter( 'excerpt_length', 'theme_slug_excerpt_length', 999 );

Please help me. Thanks in advance.

Regards Ponvendhan