diff --git a/src/wp-includes/author-template.php b/src/wp-includes/author-template.php
index 3f28492377..a4f2a1815a 100644
--- a/src/wp-includes/author-template.php
+++ b/src/wp-includes/author-template.php
@@ -86,7 +86,7 @@ function the_author( $deprecated = '', $deprecated_echo = true ) {
  *
  * @since 2.8.0
  *
- * @return string|void The author's display name.
+ * @return string|void The author's display name, empty string if unkown.
  */
 function get_the_modified_author() {
 	$last_id = get_post_meta( get_post()->ID, '_edit_last', true );
@@ -99,9 +99,9 @@ function get_the_modified_author() {
 		 *
 		 * @since 2.8.0
 		 *
-		 * @param string $display_name The author's display name.
+		 * @param string $display_name The author's display name, empty string if unkown.
 		 */
-		return apply_filters( 'the_modified_author', $last_user->display_name );
+		return apply_filters( 'the_modified_author', $last_user ? $last_user->display_name : '' );
 	}
 }