diff --git a/wp-includes/post.php b/wp-includes/post.php
index 31bf142f45..e5b35e56cf 100644
--- a/wp-includes/post.php
+++ b/wp-includes/post.php
@@ -3673,7 +3673,6 @@ function wp_unique_post_slug( $slug, $post_ID, $post_status, $post_type, $post_p
 	if ( ! is_array( $feeds ) )
 		$feeds = array();
 
-	$hierarchical_post_types = get_post_types( array('hierarchical' => true) );
 	if ( 'attachment' == $post_type ) {
 		// Attachment slugs must be unique across all types.
 		$check_sql = "SELECT post_name FROM $wpdb->posts WHERE post_name = %s AND ID != %d LIMIT 1";
@@ -3696,7 +3695,7 @@ function wp_unique_post_slug( $slug, $post_ID, $post_status, $post_type, $post_p
 			} while ( $post_name_check );
 			$slug = $alt_post_name;
 		}
-	} elseif ( in_array( $post_type, $hierarchical_post_types ) ) {
+	} elseif ( is_post_type_hierarchical( $post_type ) ) {
 		if ( 'nav_menu_item' == $post_type )
 			return $slug;
 
@@ -3704,8 +3703,8 @@ function wp_unique_post_slug( $slug, $post_ID, $post_status, $post_type, $post_p
 		 * Page slugs must be unique within their own trees. Pages are in a separate
 		 * namespace than posts so page slugs are allowed to overlap post slugs.
 		 */
-		$check_sql = "SELECT post_name FROM $wpdb->posts WHERE post_name = %s AND post_type IN ( '" . implode( "', '", esc_sql( $hierarchical_post_types ) ) . "' ) AND ID != %d AND post_parent = %d LIMIT 1";
-		$post_name_check = $wpdb->get_var( $wpdb->prepare( $check_sql, $slug, $post_ID, $post_parent ) );
+		$check_sql = "SELECT post_name FROM $wpdb->posts WHERE post_name = %s AND post_type = %s AND ID != %d AND post_parent = %d LIMIT 1";
+		$post_name_check = $wpdb->get_var( $wpdb->prepare( $check_sql, $slug, $post_type, $post_ID, $post_parent ) );
 
 		/**
 		 * Filter whether the post slug would make a bad hierarchical post slug.
diff --git a/wp-includes/version.php b/wp-includes/version.php
index 2aa56b53a0..78044c527a 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '4.1-alpha-30157';
+$wp_version = '4.1-alpha-30158';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.