diff --git a/X2UtStrings.pas b/X2UtStrings.pas
index 38b0c5b..2c8bf8f 100644
--- a/X2UtStrings.pas
+++ b/X2UtStrings.pas
@@ -22,7 +22,7 @@ type
    * @result            the formatted size.
   *}
   function FormatSize(const ABytes: Int64; AKeepBytes: Boolean = False;
-                      const AFormat = ',0.##'): String;
+                      const AFormat: String = ',0.##'): String;
 
   {** Compares two strings without case sensitivity.
    *