--- a/tool/Command.h	Fri Nov 26 11:23:19 2010 +0100
+++ b/tool/Command.h	Sat Nov 27 17:02:54 2010 +0100
@@ -112,7 +112,7 @@
         bool matchesSubstr(const string &) const;
         bool matchesAbbrev(const string &) const;
 
-        virtual string helpString() const = 0;
+        virtual string helpString(const string &) const = 0;
 
         typedef vector<string> StringVector;
         virtual void execute(const StringVector &) = 0;