diff --git a/lemonldap-ng-handler/lib/Lemonldap/NG/Handler/Main/Run.pm b/lemonldap-ng-handler/lib/Lemonldap/NG/Handler/Main/Run.pm
index 5103de5c8..a951c4c01 100644
--- a/lemonldap-ng-handler/lib/Lemonldap/NG/Handler/Main/Run.pm
+++ b/lemonldap-ng-handler/lib/Lemonldap/NG/Handler/Main/Run.pm
@@ -478,7 +478,7 @@ sub retrieveSession {
         $class->logger->debug( "now -> " . $now );
         $class->logger->debug( "_lastSeen -> " . $session->data->{_lastSeen} )
             if ( $session->data->{_lastSeen} );
-        my $delta = $now - $session->data->{_lastSeen};
+        my $delta = $now - $session->data->{_lastSeen} if ( $session->data->{_lastSeen} );
         $class->logger->debug( "now - _lastSeen = " . $delta )
             if ( $session->data->{_lastSeen} );
         $class->logger->debug( "Session timeoutActivityInterval -> "