diff --git a/htdocs/compta/prelevement/class/bonprelevement.class.php b/htdocs/compta/prelevement/class/bonprelevement.class.php
index 373615ecdfb..cc455c625bd 100644
--- a/htdocs/compta/prelevement/class/bonprelevement.class.php
+++ b/htdocs/compta/prelevement/class/bonprelevement.class.php
@@ -1719,8 +1719,11 @@ class BonPrelevement extends CommonObject
 	public static function buildRumNumber($row_code_client, $row_datec, $row_drum)
 	{
 		global $langs;
+
 		$pre = substr(dol_string_nospecial(dol_string_unaccent($langs->transnoentitiesnoconv('RUM'))), 0, 3); // Must always be on 3 char ('RUM' or 'UMR'. This is a protection against bad translation)
-		return $pre.($row_code_client ? '-'.$row_code_client : '').'-'.$row_drum.'-'.date('U', $row_datec);
+
+		// 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);
 	}
 
 
diff --git a/htdocs/core/lib/functions.lib.php b/htdocs/core/lib/functions.lib.php
index 6f85d0e6f3e..35436f9d2be 100644
--- a/htdocs/core/lib/functions.lib.php
+++ b/htdocs/core/lib/functions.lib.php
@@ -2632,7 +2632,7 @@ function dol_print_date($time, $format = '', $tzoutput = 'auto', $outputlangs =
 		$format = '%Y%m%d%H%M%S';
 	} elseif ($format == 'dayhourlogsmall') {
 		// Format not sensitive to language
-		$format = '%Y%m%d%H%M';
+		$format = '%y%m%d%H%M';
 	} elseif ($format == 'dayhourldap') {
 		$format = '%Y%m%d%H%M%SZ';
 	} elseif ($format == 'dayhourxcard') {