diff --git a/htdocs/core/tpl/extrafields_list_search_sql.tpl.php b/htdocs/core/tpl/extrafields_list_search_sql.tpl.php
index 8492160c185..bdaf963b4f5 100644
--- a/htdocs/core/tpl/extrafields_list_search_sql.tpl.php
+++ b/htdocs/core/tpl/extrafields_list_search_sql.tpl.php
@@ -27,6 +27,7 @@ if (! empty($extrafieldsobjectkey))	// $extrafieldsobject is the $object->table_
 			if (in_array($typ, array('int','double','real'))) $mode_search=1;								// Search on a numeric
 			if (in_array($typ, array('sellist','link')) && $crit != '0' && $crit != '-1') $mode_search=2;	// Search on a foreign key int
 			if (in_array($typ, array('chkbxlst','checkbox'))) $mode_search=4;	                            // Search on a multiselect field with sql type = text
+			if (is_array($crit)) $crit = implode(' ', $crit); // natural_search() expects a string
 
 			$sql .= natural_search('ef.'.$tmpkey, $crit, $mode_search);
 		}