diff --git a/cpp/SymbolicFactor.h b/cpp/SymbolicFactor.h
index 8d4b5cf44..9c0ba9a9a 100644
--- a/cpp/SymbolicFactor.h
+++ b/cpp/SymbolicFactor.h
@@ -13,6 +13,7 @@
 #include <vector>
 #include <boost/shared_ptr.hpp>
 #include "Testable.h"
+#include "Ordering.h"
 
 namespace gtsam {