diff --git a/wp-includes/ms-blogs.php b/wp-includes/ms-blogs.php
index 812ec62768..3668afcac8 100644
--- a/wp-includes/ms-blogs.php
+++ b/wp-includes/ms-blogs.php
@@ -320,7 +320,7 @@ function update_blog_details( $blog_id, $details = array() ) {
  * @since MU
  * @uses apply_filters() Calls 'blog_option_$optionname' with the option name value.
  *
- * @param int $blog_id is the id of the blog.
+ * @param int $blog_id Optional. Blog ID, can be null to refer to the current blog.
  * @param string $setting Name of option to retrieve. Should already be SQL-escaped.
  * @param string $default (optional) Default value returned if option not found.
  * @return mixed Value set for the option.
@@ -328,6 +328,9 @@ function update_blog_details( $blog_id, $details = array() ) {
 function get_blog_option( $blog_id, $setting, $default = false ) {
 	global $wpdb;
 
+	if ( null === $blog_id )
+		$blog_id = $wpdb->blogid;
+
 	$key = $blog_id . '-' . $setting . '-blog_option';
 	$value = wp_cache_get( $key, 'site-options' );
 	if ( $value == null ) {
@@ -380,14 +383,17 @@ function get_blog_option( $blog_id, $setting, $default = false ) {
  * @param int $id The blog id
  * @param string $key The option key
  * @param mixed $value The option value
+ * @return bool True on success, false on failure.
  */
 function add_blog_option( $id, $key, $value ) {
 	$id = (int) $id;
 
 	switch_to_blog($id);
-	add_option( $key, $value );
+	$return = add_option( $key, $value );
 	restore_current_blog();
-	wp_cache_set( $id . '-' . $key . '-blog_option', $value, 'site-options' );
+	if ( $return )
+		wp_cache_set( $id . '-' . $key . '-blog_option', $value, 'site-options' );
+	return $return;
 }
 
 /**
@@ -397,14 +403,17 @@ function add_blog_option( $id, $key, $value ) {
  *
  * @param int $id The blog id
  * @param string $key The option key
+ * @return bool True on success, false on failure.
  */
 function delete_blog_option( $id, $key ) {
 	$id = (int) $id;
 
 	switch_to_blog($id);
-	delete_option( $key );
+	$return = delete_option( $key );
 	restore_current_blog();
-	wp_cache_set( $id . '-' . $key . '-blog_option', '', 'site-options' );
+	if ( $return )
+		wp_cache_set( $id . '-' . $key . '-blog_option', '', 'site-options' );
+	return $return;
 }
 
 /**
@@ -415,6 +424,7 @@ function delete_blog_option( $id, $key ) {
  * @param int $id The blog id
  * @param string $key The option key
  * @param mixed $value The option value
+ * @return bool True on success, false on failrue.
  */
 function update_blog_option( $id, $key, $value, $deprecated = null ) {
 	$id = (int) $id;
@@ -423,12 +433,14 @@ function update_blog_option( $id, $key, $value, $deprecated = null ) {
 		_deprecated_argument( __FUNCTION__, '3.1' );
 
 	switch_to_blog($id);
-	update_option( $key, $value );
+	$return = update_option( $key, $value );
 	restore_current_blog();
 
 	refresh_blog_details( $id );
 
-	wp_cache_set( $id . '-' . $key . '-blog_option', $value, 'site-options');
+	if ( $return )
+		wp_cache_set( $id . '-' . $key . '-blog_option', $value, 'site-options');
+	return $return;
 }
 
 /**