diff --git a/TestSuite/abstract5.pas b/TestSuite/abstract5.pas
new file mode 100644
index 000000000..78da4cc68
--- /dev/null
+++ b/TestSuite/abstract5.pas
@@ -0,0 +1,13 @@
+{$reference PresentationFramework.dll}
+{$apptype windows}
+uses System.Windows.Controls;
+
+type
+  //Ошибка: Класс MyTextBox абстрактный и не может иметь атрибут sealed, потому что метод CreateRenderScope не реализован
+  MyTextBox = sealed class(RichTextBox)
+    
+  end;
+  
+begin 
+  new MyTextBox();
+end.
\ No newline at end of file
diff --git a/TestSuite/units/u_abstract3.pas b/TestSuite/units/u_abstract3.pas
new file mode 100644
index 000000000..8751190c4
--- /dev/null
+++ b/TestSuite/units/u_abstract3.pas
@@ -0,0 +1,16 @@
+unit u_abstract3;
+type
+  
+  t1 = abstract class
+    // обязательно видимость private
+     private function f1: byte; abstract;
+  end;
+  t2 = class(t1)
+     private function f1: byte; override := 0;
+  end;
+  
+  
+  // обязательно ещё 1 промежуточный тип между t2 и t4
+  t3 = class(t2) end;
+  
+end.
\ No newline at end of file
diff --git a/TestSuite/usesunits/use_abstract3.pas b/TestSuite/usesunits/use_abstract3.pas
new file mode 100644
index 000000000..abe728f4c
--- /dev/null
+++ b/TestSuite/usesunits/use_abstract3.pas
@@ -0,0 +1,11 @@
+uses u_abstract3;
+
+type
+  
+  // обязательно t3 - тип из другого модуля
+  //Ошибка: Абстрактный класс не может иметь атрибут sealed
+  t4 = sealed class(t3) end;
+  
+begin
+  new t4;
+end.
\ No newline at end of file
diff --git a/TreeConverter/TreeConversion/compilation_context.cs b/TreeConverter/TreeConversion/compilation_context.cs
index f378c06e5..5887f9d5c 100644
--- a/TreeConverter/TreeConversion/compilation_context.cs
+++ b/TreeConverter/TreeConversion/compilation_context.cs
@@ -2745,7 +2745,19 @@ namespace PascalABCCompiler.TreeConverter
 		
         private void check_implement_abstract_function(common_type_node cnode, function_node meth, type_node interf)
         {
+            //if (meth.field_access_level == SemanticTree.field_access_level.fal_private)
+            //    return;
         	List<SymbolInfo> sil = cnode.find_in_type(meth.name, cnode.Scope);
+            if (meth.field_access_level == SemanticTree.field_access_level.fal_private)
+            {
+                var base_type = cnode.base_type; 
+                while (base_type != null && base_type.IsAbstract)
+                {
+                    base_type = base_type.base_type;
+                }
+                if (base_type != null && !base_type.IsAbstract && base_type != SystemLibrary.SystemLibrary.object_type)
+                    return;
+            }
             function_node fn = null;
             if (sil != null)
             {