diff --git a/rtl/objpas/sysutils/disk.inc b/rtl/objpas/sysutils/disk.inc
index 2e6d5034fc..de97fb5c7f 100644
--- a/rtl/objpas/sysutils/disk.inc
+++ b/rtl/objpas/sysutils/disk.inc
@@ -110,7 +110,7 @@ begin
   Result:=False;
   ADrv:=ExtractFileDrive(Dir);
   if (ADrv<>'') and
-     (not DirectoryExists(ADrv)+DirectorySeparator)
+     (not DirectoryExists(ADrv+DirectorySeparator))
      {$IFNDEF FORCEDIR_NO_UNC_SUPPORT} and (not IsUncDrive(ADrv)){$ENDIF} then
     Exit;
   if Dir='' then