diff --git a/core/attributedef.class.inc.php b/core/attributedef.class.inc.php
index af5baa88f..d8edb8cb1 100644
--- a/core/attributedef.class.inc.php
+++ b/core/attributedef.class.inc.php
@@ -4589,7 +4589,7 @@ class AttributeCaseLog extends AttributeLongText
 				{
 					//N°5135 - add impersonation information in caselog
 					if (UserRights::IsImpersonated()){
-						$sOnBehalfOf = $sUserString = Dict::Format('UI:Archive_User_OnBehalfOf_User', UserRights::GetRealUserFriendlyName(), UserRights::GetUserFriendlyName());
+						$sOnBehalfOf = Dict::Format('UI:Archive_User_OnBehalfOf_User', UserRights::GetRealUserFriendlyName(), UserRights::GetUserFriendlyName());
 						$oCaseLog->AddLogEntry($proposedValue, $sOnBehalfOf, UserRights::GetConnectedUserId());
 					} else {
 						$oCaseLog->AddLogEntry($proposedValue);