diff --git a/cataloguing/value_builder/callnumber.pl b/cataloguing/value_builder/callnumber.pl
index 889d8c9a5b..3ed09d9fa8 100755
--- a/cataloguing/value_builder/callnumber.pl
+++ b/cataloguing/value_builder/callnumber.pl
@@ -95,7 +95,8 @@ sub plugin {
             );
         }
     # If a prefix is submited, we look for the highest itemcallnumber with this prefix, and return it incremented
-    } elsif ( $code =~ m/^[A-Z]+$/ ) {
+    } elsif ( $code =~ m/^[A-Z.\-]+$/ ) {
+        warn $code;
         my $sth = $dbh->prepare("SELECT MAX(CAST(SUBSTRING_INDEX(itemcallnumber,' ',-1) AS SIGNED)) FROM items WHERE itemcallnumber LIKE ?");
         $sth->execute($code.' %');
         if ( my $max = $sth->fetchrow ) {