diff --git a/wp-admin/includes/ajax-actions.php b/wp-admin/includes/ajax-actions.php
index 0bfc988b5a..ede374db2d 100644
--- a/wp-admin/includes/ajax-actions.php
+++ b/wp-admin/includes/ajax-actions.php
@@ -2103,7 +2103,7 @@ function wp_ajax_get_revision_diffs() {
 		wp_send_json_error();
 
 	$return = array();
-	@set_time_limit( count( $_REQUEST['compare'] ) );
+	@set_time_limit( 0 );
 
 	foreach ( $_REQUEST['compare'] as $compare_key ) {
 		list( $compare_from, $compare_to ) = explode( ':', $compare_key ); // from:to