lib/texinputs/isabelle.sty

--- a/lib/texinputs/isabelle.sty	Fri May 06 13:35:00 2011 +0200
+++ b/lib/texinputs/isabelle.sty	Fri May 06 17:52:08 2011 +0200
@@ -188,7 +188,6 @@
 
 \newcommand{\isabellestyleitunderscore}{%
 %requires underscore.sty
-\underscoreon%
 \isabellestyleit%
 \def\isacharunderscore{\_}%
 \def\isacharunderscorekeyword{\_}%