diff --git a/packages/rtl/system.pas b/packages/rtl/system.pas
index 1253699..5a805f1 100644
--- a/packages/rtl/system.pas
+++ b/packages/rtl/system.pas
@@ -80,7 +80,7 @@ type
     D3: word;
     D4: array[0..7] of byte;
   end;
-  TGUIDString = string; // ToDo: use type string when supported by compiler
+  TGUIDString = type string;
 
   TClass = class of TObject;
 
diff --git a/packages/rtl/typinfo.pas b/packages/rtl/typinfo.pas
index 6832923..df09b9a 100644
--- a/packages/rtl/typinfo.pas
+++ b/packages/rtl/typinfo.pas
@@ -251,7 +251,7 @@ type
   public
     TypeInfo: TTypeInfo external name 'typeinfo';
     Flags: NativeInt external name 'flags'; // bit vector, see pf constants above
-    Params: TProcedureParams external name 'params'; // can be null
+    Params: TProcedureParams external name 'params'; // can be null or undefined
     Index: JSValue external name 'index'; // can be undefined
     Getter: String external name 'getter'; // name of field or function
     Setter: String external name 'setter'; // name of field or function