diff --git a/TestSuite/errors/err0210.pas b/TestSuite/errors/err0210.pas
new file mode 100644
index 000000000..fe6b448da
--- /dev/null
+++ b/TestSuite/errors/err0210.pas
@@ -0,0 +1,4 @@
+begin
+  var s: string;
+  var rs := s.Copy;
+end.
\ No newline at end of file
diff --git a/TreeConverter/TreeConversion/CompilationErrors.cs b/TreeConverter/TreeConversion/CompilationErrors.cs
index 0d61bb475..08c0881c6 100644
--- a/TreeConverter/TreeConversion/CompilationErrors.cs
+++ b/TreeConverter/TreeConversion/CompilationErrors.cs
@@ -142,7 +142,10 @@ namespace PascalABCCompiler.TreeConverter
         }
         public override string ToString()
         {
-            return string.Format(StringResources.Get(ErrResourceString), values);
+            if (values != null)
+                return string.Format(StringResources.Get(ErrResourceString), values);
+            else
+                return string.Format(StringResources.Get(ErrResourceString), "");
         }
     }
 
diff --git a/TreeConverter/TreeConversion/syntax_tree_visitor.cs b/TreeConverter/TreeConversion/syntax_tree_visitor.cs
index 9b57237e7..ab290c07b 100644
--- a/TreeConverter/TreeConversion/syntax_tree_visitor.cs
+++ b/TreeConverter/TreeConversion/syntax_tree_visitor.cs
@@ -1542,7 +1542,8 @@ namespace PascalABCCompiler.TreeConverter
                 }
                 if (convertion_data_and_alghoritms.find_eq_method_in_list(fn, fnl) == null)
                 {
-                    fnl.AddElement(fn);
+                    if (!(obj != null && fn.polymorphic_state == SemanticTree.polymorphic_state.ps_static && !fn.is_extension_method))
+                        fnl.AddElement(fn);
                 }
                 si = si.Next;
             }