diff --git a/src/wp-includes/feed.php b/src/wp-includes/feed.php
index 41c7dac432..f40f41a6ad 100644
--- a/src/wp-includes/feed.php
+++ b/src/wp-includes/feed.php
@@ -560,7 +560,7 @@ function prep_atom_text_construct($data) {
  * @see get_site_icon_url()
  */
 function atom_site_icon() {
-	$url = get_site_icon_url( null, 32 );
+	$url = get_site_icon_url( 32 );
 	if ( $url ) {
 		echo "<icon>$url</icon>\n";
 	}
@@ -577,7 +577,7 @@ function rss2_site_icon() {
 		$rss_title = get_bloginfo_rss( 'name' );
 	}
 
-	$url = get_site_icon_url( null, 32 );
+	$url = get_site_icon_url( 32 );
 	if ( $url ) {
 		echo '
 <image>
diff --git a/src/wp-includes/general-template.php b/src/wp-includes/general-template.php
index 97b780a2cc..6ed04e27ad 100644
--- a/src/wp-includes/general-template.php
+++ b/src/wp-includes/general-template.php
@@ -724,14 +724,14 @@ function get_bloginfo( $show = '', $filter = 'raw' ) {
 /**
  * Returns the Site Icon URL.
  *
- * @param  null|int $blog_id Id of the blog to get the site icon for.
- * @param  int      $size    Size of the site icon.
- * @param  string   $url     Fallback url if no site icon is found.
- * @return string            Site Icon URL.
+ * @param  int    $size    Size of the site icon.
+ * @param  string $url     Fallback url if no site icon is found.
+ * @param  int    $blog_id Id of the blog to get the site icon for.
+ * @return string          Site Icon URL.
  */
-function get_site_icon_url( $blog_id = null, $size = 512, $url = '' ) {
+function get_site_icon_url( $size = 512, $url = '', $blog_id = 0 ) {
 	if ( function_exists( 'get_blog_option' ) ) {
-		if ( ! is_int( $blog_id ) ) {
+		if ( ! $blog_id ) {
 			$blog_id = get_current_blog_id();
 		}
 		$site_icon_id = get_blog_option( $blog_id, 'site_icon' );
@@ -755,22 +755,22 @@ function get_site_icon_url( $blog_id = null, $size = 512, $url = '' ) {
 /**
  * Displays the Site Icon URL.
  *
- * @param null|int $blog_id Id of the blog to get the site icon for.
- * @param int      $size    Size of the site icon.
- * @param string   $url     Fallback url if no site icon is found.
+ * @param  int    $size    Size of the site icon.
+ * @param  string $url     Fallback url if no site icon is found.
+ * @param  int    $blog_id Id of the blog to get the site icon for.
  */
-function site_icon_url( $blog_id = null, $size = 512, $url = '' ) {
-	echo esc_url( get_site_icon_url( $blog_id, $size, $url ) );
+function site_icon_url( $size = 512, $url = '', $blog_id = 0 ) {
+	echo esc_url( get_site_icon_url( $size, $url, $blog_id ) );
 }
 
 /**
  * Whether the site has a Site Icon.
  *
- * @param int|null $blog_id Optional. Blog ID. Default: Current blog.
+ * @param int $blog_id Optional. Blog ID. Default: Current blog.
  * @return bool
  */
-function has_site_icon( $blog_id = null ) {
-	return !! get_site_icon_url( $blog_id, 512 );
+function has_site_icon( $blog_id = 0 ) {
+	return !! get_site_icon_url( 512, '', $blog_id );
 }
 
 /**
@@ -2450,10 +2450,10 @@ function wp_site_icon() {
 	}
 
 	$meta_tags = array(
-		sprintf( '<link rel="icon" href="%s" sizes="32x32" />', esc_url( get_site_icon_url( null, 32 ) ) ),
-		sprintf( '<link rel="icon" href="%s" sizes="192x192" />', esc_url( get_site_icon_url( null, 192 ) ) ),
-		sprintf( '<link rel="apple-touch-icon-precomposed" href="%s">', esc_url( get_site_icon_url( null, 180 ) ) ),
-		sprintf( '<meta name="msapplication-TileImage" content="%s">', esc_url( get_site_icon_url( null, 270 ) ) ),
+		sprintf( '<link rel="icon" href="%s" sizes="32x32" />', esc_url( get_site_icon_url( 32 ) ) ),
+		sprintf( '<link rel="icon" href="%s" sizes="192x192" />', esc_url( get_site_icon_url( 192 ) ) ),
+		sprintf( '<link rel="apple-touch-icon-precomposed" href="%s">', esc_url( get_site_icon_url( 180 ) ) ),
+		sprintf( '<meta name="msapplication-TileImage" content="%s">', esc_url( get_site_icon_url( 270 ) ) ),
 	);
 
 	/**