diff --git a/htdocs/lib/functions.inc.php b/htdocs/lib/functions.inc.php
index ca3d325c928..b4d1f46b170 100644
--- a/htdocs/lib/functions.inc.php
+++ b/htdocs/lib/functions.inc.php
@@ -368,7 +368,7 @@ function dolibarr_print_phone($phone,$country="FR")
 */
 function dolibarr_trunc($string,$size=40)
 {
-    if (sizeof($string) > $size) return substr($string,0,$size).'...';
+    if (strlen($string) > $size) return substr($string,0,$size).'...';
     else return $string;  
 }