diff --git a/Orm/Xtensive.Orm/Orm/Linq/Expressions/Visitors/GenericExpressionVisitor.cs b/Orm/Xtensive.Orm/Orm/Linq/Expressions/Visitors/GenericExpressionVisitor.cs
index 015f7200b6..6d28d2afa5 100644
--- a/Orm/Xtensive.Orm/Orm/Linq/Expressions/Visitors/GenericExpressionVisitor.cs
+++ b/Orm/Xtensive.Orm/Orm/Linq/Expressions/Visitors/GenericExpressionVisitor.cs
@@ -29,10 +29,9 @@ protected override Expression VisitUnknown(Expression e)
     if (e is T mapped)
       return VisitGenericExpression(mapped);
 
-    if (e is ExtendedExpression extendedExpression && extendedExpression.ExtendedType == ExtendedExpressionType.Marker) {
-      var marker = (MarkerExpression) e;
-      var result = Visit(marker.Target);
-      if (result == marker.Target)
+    if (e is MarkerExpression { Target: var target } marker) {
+      var result = Visit(target);
+      if (result == target)
         return result;
       return new MarkerExpression(result, marker.MarkerType);
     }