Index: src/SynTree/Attribute.h
===================================================================
--- src/SynTree/Attribute.h	(revision 54c9000e4efa1fe5278b3e7542f24426b99cc070)
+++ src/SynTree/Attribute.h	(revision 3381ed7a703d0c964d6e94bffab7c58f0cdf0d17)
@@ -50,4 +50,5 @@
 	Attribute * clone() const override { return new Attribute( *this ); }
 	virtual void accept( Visitor & v ) override { v.visit( this ); }
+	virtual void accept( Visitor & v ) const override { v.visit( this ); }
 	virtual Attribute * acceptMutator( Mutator & m ) override { return m.mutate( this ); }
 	virtual void print( std::ostream & os, Indenter indent = {} ) const override;