diff --git a/PCbuild/rt.bat b/PCbuild/rt.bat
index 91b39f74314..f3c4829569e 100644
--- a/PCbuild/rt.bat
+++ b/PCbuild/rt.bat
@@ -30,7 +30,7 @@ set prefix=.\
 set suffix=
 set qmode=
 set dashO=
-set tcltk=
+set tcltk=tcltk
 
 :CheckOpts
 if "%1"=="-O" (set dashO=-O)     & shift & goto CheckOpts