diff --git a/rtl/inc/dos.inc b/rtl/inc/dos.inc
index ab060e9187..7a2432a02d 100644
--- a/rtl/inc/dos.inc
+++ b/rtl/inc/dos.inc
@@ -173,7 +173,7 @@ end;
 
 
 {$IFNDEF HAS_GETSHORTNAME}
-function GetShortName (var P: String): boolean;
+function GetShortName (var P: ShortString): boolean;
 begin
   GetShortName := true;
 end;
@@ -181,7 +181,7 @@ end;
 
 
 {$IFNDEF HAS_GETLONGNAME}
-function GetLongName (var P: String): boolean;
+function GetLongName (var P: ShortString): boolean;
 begin
   GetLongName := true;
 end;
diff --git a/rtl/inc/dosh.inc b/rtl/inc/dosh.inc
index a6fe01cc0b..78e99a5855 100644
--- a/rtl/inc/dosh.inc
+++ b/rtl/inc/dosh.inc
@@ -108,16 +108,16 @@ Procedure FindClose(Var f: SearchRec);
 {File}
 Procedure GetFAttr(var f; var attr: word);
 Procedure GetFTime(var f; var time: longint);
-Function  FSearch(path: pathstr; dirlist: string): pathstr;
+Function  FSearch(path: pathstr; dirlist: shortstring): pathstr;
 Function  FExpand(const path: pathstr): pathstr;
 Procedure FSplit(path: pathstr; var dir: dirstr; var name: namestr; var ext: extstr);
-function  GetShortName(var p : String) : boolean;
-function  GetLongName(var p : String) : boolean;
+function  GetShortName(var p : ShortString) : boolean;
+function  GetLongName(var p : ShortString) : boolean;
 
 {Environment}
 Function  EnvCount: longint;
-Function  EnvStr (Index: longint): string;
-Function  GetEnv(envvar: string): string;
+Function  EnvStr (Index: longint): shortstring;
+Function  GetEnv(envvar: shortstring): shortstring;
 
 {Misc}
 Procedure SetFAttr(var f; attr: word);