diff -ur boost_1_57_0.orig/boost/signals2/trackable.hpp boost_1_57_0/boost/signals2/trackable.hpp
--- boost_1_57_0.orig/boost/signals2/trackable.hpp	2014-09-27 00:30:52.000000000 +0200
+++ boost_1_57_0/boost/signals2/trackable.hpp	2015-07-29 19:50:33.467831302 +0200
@@ -18,6 +18,7 @@
 
 #include <boost/assert.hpp>
 #include <boost/shared_ptr.hpp>
+#include <boost/weak_ptr.hpp>
 
 namespace boost {
   namespace signals2 {