diff --git a/rtl/inc/astrings.inc b/rtl/inc/astrings.inc
index bbcf5dd52d..f141501751 100644
--- a/rtl/inc/astrings.inc
+++ b/rtl/inc/astrings.inc
@@ -292,7 +292,7 @@ procedure fpc_AnsiStr_Concat_multi (var DestS:RawByteString;const sarr:array of
 Var
   lowstart,
   nonemptystart,
-  i           : Longint;
+  i           : NativeInt;
   p,pc        : pointer;
   Size,NewLen,
   OldDestLen  : SizeInt;