diff --git a/htdocs/compta/prelevement/class/bonprelevement.class.php b/htdocs/compta/prelevement/class/bonprelevement.class.php
index cc455c625bd..7bf8f87d0f0 100644
--- a/htdocs/compta/prelevement/class/bonprelevement.class.php
+++ b/htdocs/compta/prelevement/class/bonprelevement.class.php
@@ -1723,7 +1723,7 @@ class BonPrelevement extends CommonObject
 		$pre = substr(dol_string_nospecial(dol_string_unaccent($langs->transnoentitiesnoconv('RUM'))), 0, 3); // Must always be on 3 char ('RUM' or 'UMR'. This is a protection against bad translation)
 
 		// 3 char + '-' + 12 + '-' + id + '-' + code 		Must be lower than 32.
-		return $pre.'-'.dol_print_date($row_datec, 'dayhourlogsmall').'-'.dol_trunc($row_drum.($row_code_client ? '-'.$row_code_client : ''), 15, 'right', 'UTF-8', 1);
+		return $pre.'-'.dol_print_date($row_datec, 'dayhourlogsmall').'-'.dol_trunc($row_drum.($row_code_client ? '-'.$row_code_client : ''), 13, 'right', 'UTF-8', 1);
 	}