diff --git a/Compiler/PCU/PCUReader.cs b/Compiler/PCU/PCUReader.cs
index 02dbdc62e..fcca851b7 100644
--- a/Compiler/PCU/PCUReader.cs
+++ b/Compiler/PCU/PCUReader.cs
@@ -2211,6 +2211,10 @@ namespace PascalABCCompiler.PCU
             ctn.type_special_kind = tsk;
             if (ctn.full_name == "PABCSystem.BinaryFile")
                 ctn.type_special_kind = SemanticTree.type_special_kind.binary_file;
+            if (ctn.type_special_kind != SemanticTree.type_special_kind.set_type)
+            {
+                SystemLibrary.SystemLibrary.init_reference_type(ctn);
+            }
             if (type_is_generic_definition)
             {
                 foreach (common_type_node par in type_params)
@@ -2219,14 +2223,11 @@ namespace PascalABCCompiler.PCU
                     ReadTypeParameterEliminations(par);
                 }
             }
-            type_node elemnet_type = null;
+            type_node element_type = null;
             if (CanReadObject())
-                elemnet_type = GetTypeReference();
-            ctn.element_type = elemnet_type;
-            if (ctn.type_special_kind != SemanticTree.type_special_kind.set_type)
-            {
-                SystemLibrary.SystemLibrary.init_reference_type(ctn);
-            }
+                element_type = GetTypeReference();
+            ctn.element_type = element_type;
+            
             if (ctn.type_special_kind == SemanticTree.type_special_kind.set_type)
             {
                 ctn = compilation_context.AddTypeToSetTypeList(ctn);
diff --git a/TestSuite/errors/err0393.pas b/TestSuite/errors/err0393.pas
new file mode 100644
index 000000000..6bab2156b
--- /dev/null
+++ b/TestSuite/errors/err0393.pas
@@ -0,0 +1,12 @@
+type
+  t0 = class end;
+  
+  t1<T> = class
+  where T: t0;
+    
+  end;
+  
+begin
+  // Компилируется, а не должно
+  var a: t1<byte>;
+end.
\ No newline at end of file
diff --git a/TestSuite/units/u_where2.pas b/TestSuite/units/u_where2.pas
new file mode 100644
index 000000000..2f108cde0
--- /dev/null
+++ b/TestSuite/units/u_where2.pas
@@ -0,0 +1,12 @@
+unit u_where2;
+
+type
+  
+  t0<T> = class
+  where T: t0<T>;
+    
+    procedure p1(a: T); virtual := exit;
+    
+  end;
+  
+end.
\ No newline at end of file
diff --git a/TestSuite/usesunits/use_where2.pas b/TestSuite/usesunits/use_where2.pas
new file mode 100644
index 000000000..58912ddf1
--- /dev/null
+++ b/TestSuite/usesunits/use_where2.pas
@@ -0,0 +1,19 @@
+uses u_where2;
+
+var i: integer;
+type
+  
+  t1 = class(t0<t1>)
+    
+    procedure p1(a: t1); override;
+    begin
+      i := 1;  
+    end;
+    
+  end;
+  
+begin 
+var obj := new t1;
+obj.p1(obj);
+assert(i = 1);
+end.
\ No newline at end of file
diff --git a/TreeConverter/TreeRealization/generics.cs b/TreeConverter/TreeRealization/generics.cs
index 7811a950f..8996ff0ec 100644
--- a/TreeConverter/TreeRealization/generics.cs
+++ b/TreeConverter/TreeRealization/generics.cs
@@ -166,6 +166,10 @@ namespace PascalABCCompiler.TreeRealization
                         return new SimpleSemanticError(null, "PARAMETER_{0}_MUST_BE_DERIVED_FROM_{1}", tn.PrintableName, base_type.name);
                     }
                 }
+                if (gpe.base_class != null && gpe.base_class != SystemLibrary.SystemLibrary.object_type && tn.is_value && !gpe.base_class.is_value && gpe.base_class != SystemLibrary.SystemLibrary.value_type)
+                {
+                    return new SimpleSemanticError(null, "PARAMETER_{0}_MUST_BE_REFERENCE_TYPE", tn.PrintableName);
+                }
                 foreach (type_node interf in gpe.implementing_interfaces)
                 {
                     type_node di = generic_convertions.determine_type(interf, tparams, method_param_types);