diff --git a/my/lib.php b/my/lib.php
index 65e4f7ef974..1ed7676ceed 100644
--- a/my/lib.php
+++ b/my/lib.php
@@ -244,7 +244,7 @@ function my_reset_page_for_all_users(
                   JOIN {context} ctx ON ctx.instanceid = p.userid AND ctx.contextlevel = :usercontextlevel
                   JOIN {block_instances} bi ON bi.parentcontextid = ctx.id
                    AND bi.pagetypepattern = :pagetypepattern
-                   AND (bi.subpagepattern IS NULL OR bi.subpagepattern = " . $DB->sql_concat("''", 'p.id') . ")
+                   AND (bi.subpagepattern IS NULL OR bi.subpagepattern = " . $DB->sql_cast_to_char('p.id') . ")
                  WHERE p.private = :private
                    AND p.name = :name
                    AND p.userid $infragment";