--- a/README	Tue Jul 15 17:25:53 2014 +0200
+++ b/README	Wed Sep 09 11:24:19 2015 +0100
@@ -12,7 +12,7 @@
 
 The repository can be checked using Isabelle 2013-2.
 
-  isabelle build -d . PIP
+  isabelle build -c -v -d . PIP
 
 
 Othe directories are: