Index: src/natools-s_expressions-printers-pretty-config.adb
==================================================================
--- src/natools-s_expressions-printers-pretty-config.adb
+++ src/natools-s_expressions-printers-pretty-config.adb
@@ -16,11 +16,11 @@
 
 package body Natools.S_Expressions.Printers.Pretty.Config is
 
    procedure Read_Screen_Offset
      (Expression : in out Lockable.Descriptor'Class;
-      Value : out Screen_Offset;
+      Value : in out Screen_Offset;
       Has_Value : out Boolean);
       --  Decode a screen offset from a S-expression
 
    procedure Update_Casing
      (Casing : in out Encodings.Hex_Casing;
@@ -37,11 +37,11 @@
    -- Local Helper Subprograms --
    ------------------------------
 
    procedure Read_Screen_Offset
      (Expression : in out Lockable.Descriptor'Class;
-      Value : out Screen_Offset;
+      Value : in out Screen_Offset;
       Has_Value : out Boolean)
    is
       Result : Screen_Offset := 0;
    begin
       Has_Value := False;
@@ -554,11 +554,11 @@
       State : in out Parameters;
       Context : in Boolean;
       Cmd : in out Lockable.Descriptor'Class)
    is
       pragma Unreferenced (Self, Context);
-      Value : Screen_Offset;
+      Value : Screen_Offset := 0;
       Has_Value : Boolean;
    begin
       Cmd.Next;
       Read_Screen_Offset (Cmd, Value, Has_Value);
       if Has_Value and then Value /= 0 then