diff --git a/Koha/SearchEngine/Elasticsearch/QueryBuilder.pm b/Koha/SearchEngine/Elasticsearch/QueryBuilder.pm
index d950891175..98a2d590b8 100644
--- a/Koha/SearchEngine/Elasticsearch/QueryBuilder.pm
+++ b/Koha/SearchEngine/Elasticsearch/QueryBuilder.pm
@@ -491,7 +491,7 @@ sub _convert_sort_fields {
 
     # Convert the fields and orders, drop anything we don't know about.
     grep { $_->{field} } map {
-        my ( $f, $d ) = split /_/;
+        my ( $f, $d ) = /(.+)_(.+)/;
         {
             field     => $sort_field_convert{$f},
             direction => $sort_order_convert{$d}