diff --git a/gtsam/base/FastSet.h b/gtsam/base/FastSet.h
index 5fdbcfd73..73df17b0d 100644
--- a/gtsam/base/FastSet.h
+++ b/gtsam/base/FastSet.h
@@ -21,6 +21,7 @@
 #include <gtsam/base/FastDefaultAllocator.h>
 #include <boost/mpl/has_xxx.hpp>
 #include <boost/utility/enable_if.hpp>
+#include <boost/serialization/serialization.hpp>
 #include <boost/serialization/nvp.hpp>
 #include <boost/serialization/set.hpp>
 #include <set>