diff --git a/wp-admin/includes/media.php b/wp-admin/includes/media.php
index 4b9e41330d..c81e2cbc36 100644
--- a/wp-admin/includes/media.php
+++ b/wp-admin/includes/media.php
@@ -1245,7 +1245,7 @@ function get_media_item( $attachment_id, $args = null ) {
 	elseif ( isset( $_POST ) && count( $_POST ) ) // Like for async-upload where $_GET['post_id'] isn't set
 		$calling_post_id = $post->post_parent;
 	if ( 'image' == $type && $calling_post_id && current_theme_supports( 'post-thumbnails', get_post_type( $calling_post_id ) ) && get_post_thumbnail_id( $calling_post_id ) != $attachment_id )
-		$thumbnail = "<a class='wp-post-thumbnail' href='#' onclick='WPSetAsThumbnail(\"$attachment_id\");return false;'>" . esc_html__( "Use as thumbnail" ) . "</a>";
+		$thumbnail = "<a class='wp-post-thumbnail' id='wp-post-thumbnail-" . $attachment_id . "' href='#' onclick='WPSetAsThumbnail(\"$attachment_id\");return false;'>" . esc_html__( "Use as thumbnail" ) . "</a>";
 
 	if ( ( $send || $thumbnail || $delete ) && !isset($form_fields['buttons']) )
 		$form_fields['buttons'] = array('tr' => "\t\t<tr class='submit'><td></td><td class='savesend'>$send $thumbnail $delete</td></tr>\n");
diff --git a/wp-admin/js/set-post-thumbnail.dev.js b/wp-admin/js/set-post-thumbnail.dev.js
index d8ea68b1db..508577fc8e 100644
--- a/wp-admin/js/set-post-thumbnail.dev.js
+++ b/wp-admin/js/set-post-thumbnail.dev.js
@@ -1,5 +1,5 @@
 function WPSetAsThumbnail(id){
-	var $link = jQuery('#media-item-' + id + ' a.wp-post-thumbnail');
+	var $link = jQuery('a#wp-post-thumbnail-' + id);
 
 	$link.text( setPostThumbnailL10n.saving );
 	jQuery.post(ajaxurl, {
diff --git a/wp-admin/js/set-post-thumbnail.js b/wp-admin/js/set-post-thumbnail.js
index 6ba67ee24c..a2c63af42f 100644
--- a/wp-admin/js/set-post-thumbnail.js
+++ b/wp-admin/js/set-post-thumbnail.js
@@ -1 +1 @@
-function WPSetAsThumbnail(id){var $link=jQuery("#media-item-"+id+" a.wp-post-thumbnail");$link.text(setPostThumbnailL10n.saving);jQuery.post(ajaxurl,{action:"set-post-thumbnail",post_id:post_id,thumbnail_id:id,cookie:encodeURIComponent(document.cookie)},function(str){var win=window.dialogArguments||opener||parent||top;$link.text(setPostThumbnailL10n.setThumbnail);if(str=="0"){alert(setPostThumbnailL10n.error)}else{jQuery("a.wp-post-thumbnail").show();$link.text(setPostThumbnailL10n.done);$link.fadeOut(2000);win.WPSetThumbnailID(id);win.WPSetThumbnailHTML(str)}})};
\ No newline at end of file
+function WPSetAsThumbnail(id){var $link=jQuery("a#wp-post-thumbnail-"+id);$link.text(setPostThumbnailL10n.saving);jQuery.post(ajaxurl,{action:"set-post-thumbnail",post_id:post_id,thumbnail_id:id,cookie:encodeURIComponent(document.cookie)},function(str){var win=window.dialogArguments||opener||parent||top;$link.text(setPostThumbnailL10n.setThumbnail);if(str=="0"){alert(setPostThumbnailL10n.error)}else{jQuery("a.wp-post-thumbnail").show();$link.text(setPostThumbnailL10n.done);$link.fadeOut(2000);win.WPSetThumbnailID(id);win.WPSetThumbnailHTML(str)}})};
\ No newline at end of file
diff --git a/wp-includes/script-loader.php b/wp-includes/script-loader.php
index 058b40b1bc..1262822c58 100644
--- a/wp-includes/script-loader.php
+++ b/wp-includes/script-loader.php
@@ -382,7 +382,7 @@ function wp_default_scripts( &$scripts ) {
 		$scripts->add( 'image-edit', "/wp-admin/js/image-edit$suffix.js", array('jquery', 'json2', 'imgareaselect'), '20091111' );
 		$scripts->add_data( 'image-edit', 'group', 1 );
 
-		$scripts->add( 'set-post-thumbnail', "/wp-admin/js/set-post-thumbnail$suffix.js", array( 'jquery' ), '20091210' );
+		$scripts->add( 'set-post-thumbnail', "/wp-admin/js/set-post-thumbnail$suffix.js", array( 'jquery' ), '20091210b' );
 		$scripts->add_data( 'set-post-thumbnail', 'group', 1 );
 		$scripts->localize( 'set-post-thumbnail', 'setPostThumbnailL10n', array(
 			'setThumbnail' => __( 'Use as thumbnail' ),