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/**
 * Add Favicon
 * 
 * @author Bill Erickson
 * @link http://www.billerickson.net/code/multiple-sizes-favicon/
 */
function be_favicon() {
	echo '<link rel="icon" href="' . get_stylesheet_directory_uri() . '/images/favicon-152.png">';
	echo '<!--[if IE]><link rel="shortcut icon" href="' . get_stylesheet_directory_uri() . '/images/favicon.ico"><![endif]-->';	
}
add_action( 'wp_head', 'be_favicon' );
remove_action( 'wp_head', 'genesis_load_favicon' );

<?php
//* Do NOT include the opening php tag shown above. Copy the code shown below.

//* Display a custom favicon
add_filter( 'genesis_pre_load_favicon', 'sp_favicon_filter' );
function sp_favicon_filter( $favicon_url ) {
	return 'http://www.mydomain.com/wp-content/themes/genesis/images/favicon.ico';
}