diff -r e19cb4c11409 -r 299f6a8faccc src/Pure/Tools/mkroot.scala
--- a/src/Pure/Tools/mkroot.scala	Tue Mar 09 20:00:44 2021 +0100
+++ b/src/Pure/Tools/mkroot.scala	Tue Mar 09 21:11:05 2021 +0100
@@ -71,6 +71,7 @@
 
       File.write(root_tex,
 """\documentclass[11pt,a4paper]{article}
+\""" + """usepackage[T1]{fontenc}
 \""" + """usepackage{isabelle,isabellesym}
 
 % further packages required for unusual symbols (see also