diff --git a/gtsam_unstable/partition/GenericGraph.h b/gtsam_unstable/partition/GenericGraph.h
index ec0027635..3dc640e97 100644
--- a/gtsam_unstable/partition/GenericGraph.h
+++ b/gtsam_unstable/partition/GenericGraph.h
@@ -12,6 +12,7 @@
 #include <list>
 #include <vector>
 #include <stdexcept>
+#include <string>
 #include <boost/shared_ptr.hpp>
 
 #include "PartitionWorkSpace.h"