diff --git a/src/wp-admin/includes/class-wp-posts-list-table.php b/src/wp-admin/includes/class-wp-posts-list-table.php
index cca5a1e..ebe173f 100644
--- a/src/wp-admin/includes/class-wp-posts-list-table.php
+++ b/src/wp-admin/includes/class-wp-posts-list-table.php
@@ -137,7 +137,19 @@ class WP_Posts_List_Table extends WP_List_Table {
 	 * @return string The value of 'orderby'.
 	 */
 	protected function get_orderby() {
-		return strtolower( get_query_var( 'orderby' ) );
+		$orderby = get_query_var( 'orderby' );
+
+		if ( is_string( $orderby ) ){
+			return strtolower( $orderby );
+		} else {
+			$keys = array_keys( $orderby );
+			// Checks if is a Numeric Array or Associative
+			if ( $keys !== range( 0, count( $orderby ) - 1 ) ){
+				return array_map( 'strtolower', $keys );
+			} else {
+				return array_map( 'strtolower', $orderby );
+			}
+		}
 	}
 
 	/**
@@ -149,7 +161,17 @@ class WP_Posts_List_Table extends WP_List_Table {
 	 * @return string The value of 'order'.
 	 */
 	protected function get_order() {
-		return strtolower( get_query_var( 'order' ) );
+		$orderby = get_query_var( 'orderby' );
+		if ( is_string( $orderby ) ){
+			return strtolower( get_query_var( 'order' ) );
+		} else {
+			// Checks if is a Numeric Array or Associative
+			if ( array_keys( $orderby ) !== range( 0, count( $orderby ) - 1 ) ){
+				return array_map( 'strtolower', array_values( $orderby ) );
+			} else {
+				return strtolower( get_query_var( 'order' ) );
+			}
+		}
 	}
 
 	/**