diff --git a/core/cmdbchangeop.class.inc.php b/core/cmdbchangeop.class.inc.php
index 0d43f0856..8bf575c74 100644
--- a/core/cmdbchangeop.class.inc.php
+++ b/core/cmdbchangeop.class.inc.php
@@ -350,21 +350,30 @@ class CMDBChangeOpSetAttributeURL extends CMDBChangeOpSetAttribute
 	{
 		$aParams = array
 		(
-			"category" => "core/cmdb",
-			"key_type" => "",
-			"name_attcode" => "change",
-			"state_attcode" => "",
-			"reconc_keys" => array(),
-			"db_table" => "priv_changeop_setatt_url",
-			"db_key_field" => "id",
+			"category"            => "core/cmdb",
+			"key_type"            => "",
+			"name_attcode"        => "change",
+			"state_attcode"       => "",
+			"reconc_keys"         => array(),
+			"db_table"            => "priv_changeop_setatt_url",
+			"db_key_field"        => "id",
 			"db_finalclass_field" => "",
 		);
 		MetaModel::Init_Params($aParams);
 		MetaModel::Init_InheritAttributes();
-		// N°4910 Old value might not comply with the current validation pattern -> force it to anything
-		MetaModel::Init_AddAttribute(new AttributeURL("oldvalue", array("allowed_values"=>null, "sql"=>"oldvalue", "target" => '_blank', "default_value"=>null, "is_null_allowed"=>true, "depends_on"=>array(), "validation_pattern" => '.*')));
-		MetaModel::Init_AddAttribute(new AttributeURL("newvalue", array("allowed_values"=>null, "sql"=>"newvalue", "target" => '_blank', "default_value"=>null, "is_null_allowed"=>true, "depends_on"=>array())));
-		
+
+		// N°4910 (oldvalue), N°5423 (newvalue)
+		// We cannot have validation here, as AttributeUrl validation is field dependant.
+		// The validation will be done when editing the iTop object, it isn't the history API responsibility
+		//
+		// Pattern is retrieved using this order :
+		// 1.  try to get the pattern from the field definition (datamodel)
+		// 2. from the iTop config
+		// 3. config parameter default value
+		// see \AttributeURL::GetValidationPattern
+		MetaModel::Init_AddAttribute(new AttributeURL("oldvalue", array("allowed_values" => null, "sql" => "oldvalue", "target" => '_blank', "default_value" => null, "is_null_allowed" => true, "depends_on" => array(), "validation_pattern" => '.*')));
+		MetaModel::Init_AddAttribute(new AttributeURL("newvalue", array("allowed_values" => null, "sql" => "newvalue", "target" => '_blank', "default_value" => null, "is_null_allowed" => true, "depends_on" => array(), "validation_pattern" => '.*')));
+
 		// Display lists
 		MetaModel::Init_SetZListItems('details', array('date', 'userinfo', 'attcode', 'oldvalue', 'newvalue')); // Attributes to be displayed for the complete details
 		MetaModel::Init_SetZListItems('list', array('date', 'userinfo', 'attcode', 'oldvalue', 'newvalue')); // Attributes to be displayed for a list