diff --git a/.gitattributes b/.gitattributes
index 814f222e99..e76bc63ff7 100644
--- a/.gitattributes
+++ b/.gitattributes
@@ -11902,6 +11902,7 @@ tests/webtbs/tw2031.pp svneol=native#text/plain
 tests/webtbs/tw2037.pp svneol=native#text/plain
 tests/webtbs/tw2040.pp svneol=native#text/plain
 tests/webtbs/tw2041.pp svneol=native#text/plain
+tests/webtbs/tw20421.pp svneol=native#text/pascal
 tests/webtbs/tw2045.pp svneol=native#text/plain
 tests/webtbs/tw2046a.pp svneol=native#text/plain
 tests/webtbs/tw2059.pp svneol=native#text/plain
diff --git a/tests/webtbs/tw20421.pp b/tests/webtbs/tw20421.pp
new file mode 100644
index 0000000000..698c767715
--- /dev/null
+++ b/tests/webtbs/tw20421.pp
@@ -0,0 +1,37 @@
+{ %norun}
+program tw20421;
+
+{$mode delphi}
+
+type
+  TAncestor = class
+  private
+    function GetTest(index: integer): integer;
+  public
+    property test[index: integer]: integer read GetTest;
+  end;
+
+  TDescendant = class(TAncestor)
+  private
+    procedure SetTest(index, value: integer);
+  public
+    property test write SetTest;
+  end;
+
+{ TAncestor }
+
+function TAncestor.GetTest(index: integer): integer;
+begin
+
+end;
+
+{ TDescendant }
+
+procedure TDescendant.SetTest(index, value: integer);
+begin
+
+end;
+
+begin
+
+end.
\ No newline at end of file