diff --git a/backup/restorelib.php b/backup/restorelib.php
index c1125c9909d..f2cb989a4be 100644
--- a/backup/restorelib.php
+++ b/backup/restorelib.php
@@ -250,7 +250,7 @@
         do {
             if ($counter) {
                 $suffixfull = " ".get_string("copy")." ".$counter;
-                $suffixshort = "-".$counter;
+                $suffixshort = "_".$counter;
             } else {
                 $suffixfull = "";
                 $suffixshort = "";