diff -r ad483acf1654 -r 6a2a33ad261b lemon/dfs.h
--- a/lemon/dfs.h	Tue Dec 02 15:33:22 2008 +0000
+++ b/lemon/dfs.h	Fri Dec 05 00:22:47 2008 +0100
@@ -1625,7 +1625,7 @@
     ///
     /// \pre Either \ref run(Node) "run()" or \ref init()
     /// must be called before using this function.
-    bool reached(Node v) { return (*_reached)[v]; }
+    bool reached(Node v) const { return (*_reached)[v]; }
 
     ///@}