diff --git a/gtsam_unstable/slam/SmartProjectionFactorsCreator.h b/gtsam_unstable/slam/SmartProjectionFactorsCreator.h
index 6f10381a0..5ab4984f5 100644
--- a/gtsam_unstable/slam/SmartProjectionFactorsCreator.h
+++ b/gtsam_unstable/slam/SmartProjectionFactorsCreator.h
@@ -24,6 +24,8 @@
 #include <boost/foreach.hpp>
 #include <boost/assign.hpp>
 #include <boost/assign/std/vector.hpp>
+using namespace boost::assign;
+
 #include <fstream>
 #include <iostream>
 #include <utility>