diff --git a/tie_example.cpp b/tie_example.cpp
index 206f61e..a2462df 100644
--- a/tie_example.cpp
+++ b/tie_example.cpp
@@ -19,6 +19,7 @@
 #include <set>
 #include <algorithm>
 #include <iostream>
+#include <iterator>   // std::distance
 // Note: tie() use to live in boost/utility.hpp, but
 // not it is part of the more general Boost Tuple Library.
 #include <boost/tuple/tuple.hpp>