diff --git a/wp-admin/includes/class-wp-media-list-table.php b/wp-admin/includes/class-wp-media-list-table.php
index 44f2b7907c..0e29d7f688 100644
--- a/wp-admin/includes/class-wp-media-list-table.php
+++ b/wp-admin/includes/class-wp-media-list-table.php
@@ -84,13 +84,11 @@ class WP_Media_List_Table extends WP_List_Table {
 	}
 
 	function extra_tablenav( $which ) {
-		global $post_type;
-		$post_type_obj = get_post_type_object( $post_type );
 ?>
 		<div class="alignleft actions">
 <?php
 		if ( 'top' == $which && !is_singular() && !$this->detached && !$this->is_trash ) {
-			$this->months_dropdown( $post_type );
+			$this->months_dropdown( 'attachment' );
 
 			do_action( 'restrict_manage_posts' );
 			submit_button( __( 'Filter' ), 'secondary', false, false, array( 'id' => 'post-query-submit' ) );
diff --git a/wp-admin/includes/screen.php b/wp-admin/includes/screen.php
index 9ee21d020a..0416d11f23 100644
--- a/wp-admin/includes/screen.php
+++ b/wp-admin/includes/screen.php
@@ -490,6 +490,10 @@ final class WP_Screen {
 					$taxonomy = 'post_tag';
 				$id = 'edit-' . $taxonomy;
 				break;
+			case 'upload' :
+				if ( null === $post_type )
+					$post_type = 'attachment';
+				break;
 		}
 
 		if ( $is_network ) {