--- a/doc-src/IsarImplementation/style.sty	Sun Nov 27 12:52:52 2011 +0100
+++ b/doc-src/IsarImplementation/style.sty	Sun Nov 27 13:12:42 2011 +0100
@@ -64,7 +64,7 @@
 \newcommand{\isasymTHEOREM}{\isakeyword{theorem}}
 \newcommand{\isasymDEFINITION}{\isakeyword{definition}}
 
-\isabellestyle{itunderscore}
+\isabellestyle{literal}
 
 \railtermfont{\isabellestyle{tt}}
 \railnontermfont{\isabellestyle{itunderscore}}