diff --git a/rtl/inc/system.fpd b/rtl/inc/system.fpd
index b4cbbedfb0..5f2eea9736 100644
--- a/rtl/inc/system.fpd
+++ b/rtl/inc/system.fpd
@@ -57,5 +57,8 @@ Procedure SetLength(Var S : AStringType; Len : Integer);
 Procedure SetLength(Var A : DynArrayType; Len : Integer);
 Function Length(S : AStringType) : Integer;
 Function Length(A : DynArrayType) : Integer;
-Procedure WriteStr(Var S : String; Args : Arguments);
-Procedure ReadStr(Var S : String; Args : Arguments);
+Procedure WriteStr(Out S : String; Args : Arguments);
+Procedure ReadStr(Const S : String; Args : Arguments);
+Procedure Pack(Const A : UnpackedArrayType; StartIndex : TIndexType; Out Z : PackedArrayType);
+Procedure UnPack(Const Z : PackedArrayType; Out A : UnpackedArrayType; StartIndex : TIndexType);
+