diff --git a/.gitattributes b/.gitattributes
index bdb4de6add..984851d75a 100644
--- a/.gitattributes
+++ b/.gitattributes
@@ -9645,6 +9645,8 @@ tests/webtbs/tw9894a.pp svneol=native#text/plain
 tests/webtbs/tw9897.pp svneol=native#text/plain
 tests/webtbs/tw9918.pp svneol=native#text/plain
 tests/webtbs/tw9919.pp -text
+tests/webtbs/tw9985.pp svneol=native#text/plain
+tests/webtbs/tw9985a.pp svneol=native#text/plain
 tests/webtbs/ub1873.pp svneol=native#text/plain
 tests/webtbs/ub1883.pp svneol=native#text/plain
 tests/webtbs/uw0555.pp svneol=native#text/plain
diff --git a/rtl/unix/dos.pp b/rtl/unix/dos.pp
index 995a677a64..9f728efebb 100644
--- a/rtl/unix/dos.pp
+++ b/rtl/unix/dos.pp
@@ -388,13 +388,13 @@ var
 Function AddDisk(const path:string) : byte;
 begin
   if not (DriveStr[Drives]=nil) then
-   FreeMem(DriveStr[Drives],StrLen(DriveStr[Drives])+1);
+   FreeMem(DriveStr[Drives]);
   GetMem(DriveStr[Drives],length(Path)+1);
   StrPCopy(DriveStr[Drives],path);
+  AddDisk:=Drives;
   inc(Drives);
   if Drives>26 then
     Drives:=4;
-  AddDisk:=Drives; 
 end;
 
 
@@ -424,6 +424,19 @@ Begin
 End;
 
 
+
+Procedure FreeDriveStr;
+var
+  i: longint;
+begin
+  for i:=low(drivestr) to high(drivestr) do
+    if assigned(drivestr[i]) then
+      begin
+        freemem(drivestr[i]);
+        drivestr[i]:=nil;
+      end;
+end;
+
 {******************************************************************************
                        --- Findfirst FindNext ---
 ******************************************************************************}
@@ -895,4 +908,6 @@ End;
                             --- Initialization ---
 ******************************************************************************}
 
+Finalization
+  FreeDriveStr;
 End.
diff --git a/rtl/unix/sysutils.pp b/rtl/unix/sysutils.pp
index 4051967082..cfd8eeecae 100644
--- a/rtl/unix/sysutils.pp
+++ b/rtl/unix/sysutils.pp
@@ -705,19 +705,19 @@ Const
     '/.'
     );
 var
-  Drives   : byte;
+  Drives   : byte = 4;
   DriveStr : array[4..26] of pchar;
 
 Function AddDisk(const path:string) : Byte;
 begin
   if not (DriveStr[Drives]=nil) then
-   FreeMem(DriveStr[Drives],StrLen(DriveStr[Drives])+1);
+   FreeMem(DriveStr[Drives]);
   GetMem(DriveStr[Drives],length(Path)+1);
   StrPCopy(DriveStr[Drives],path);
+  Result:=Drives;
   inc(Drives);
   if Drives>26 then
    Drives:=4;
-  Result:=Drives;
 end;
 
 
@@ -746,6 +746,20 @@ Begin
 End;
 
 
+Procedure FreeDriveStr;
+var
+  i: longint;
+begin
+  for i:=low(drivestr) to high(drivestr) do
+    if assigned(drivestr[i]) then
+      begin
+        freemem(drivestr[i]);
+        drivestr[i]:=nil;
+      end;
+end;
+
+
+
 Function GetCurrentDir : String;
 begin
   GetDir (0,Result);
@@ -1155,5 +1169,6 @@ Initialization
   InitInternational;    { Initialize internationalization settings }
   SysConfigDir:='/etc'; { Initialize system config dir }
 Finalization
+  FreeDriveStr;
   DoneExceptions;
 end.
diff --git a/tests/webtbs/tw9985.pp b/tests/webtbs/tw9985.pp
new file mode 100644
index 0000000000..09872a88e9
--- /dev/null
+++ b/tests/webtbs/tw9985.pp
@@ -0,0 +1,25 @@
+{ %opt=-gh }
+
+{$mode objfpc}
+
+uses SysUtils;
+
+var
+  DiskNum: Byte;
+begin
+  HaltOnNotReleased := true;
+  Writeln(DiskFree(3), '/', DiskSize(3));
+
+  { Now get disk / by AddDisk. DiskFree and DiskSize below should return
+    the same (well, assuming that nothing was writeen to disk between
+    calls...). }
+{$ifdef unix}
+  DiskNum := AddDisk('/');
+{$else}
+  { dos/windows/os/2 ... Still needs other cases for other OSes }
+  DiskNum := AddDisk('C:');
+{$endif}
+  Writeln(DiskFree(DiskNum), '/', DiskSize(DiskNum));  
+  if (disksize(3)<>disksize(disknum)) then
+    halt(1);
+end.
diff --git a/tests/webtbs/tw9985a.pp b/tests/webtbs/tw9985a.pp
new file mode 100644
index 0000000000..bad4bf23f0
--- /dev/null
+++ b/tests/webtbs/tw9985a.pp
@@ -0,0 +1,25 @@
+{ %opt=-gh }
+
+{$mode objfpc}
+
+uses Dos;
+
+var
+  DiskNum: Byte;
+begin
+  HaltOnNotReleased := true;
+  Writeln(DiskFree(3), '/', DiskSize(3));
+
+  { Now get disk / by AddDisk. DiskFree and DiskSize below should return
+    the same (well, assuming that nothing was writeen to disk between
+    calls...). }
+{$ifdef unix}
+  DiskNum := AddDisk('/');
+{$else} 
+  { dos/windows/os/2 ... Still needs other cases for other OSes }
+  DiskNum := AddDisk('C:');
+{$endif}
+  Writeln(DiskFree(DiskNum), '/', DiskSize(DiskNum));
+  if (disksize(3)<>disksize(disknum)) then
+    halt(1);
+end.