diff --git a/gtsam/linear/SubgraphPreconditioner.h b/gtsam/linear/SubgraphPreconditioner.h
index c1600dd45..e74b92df1 100644
--- a/gtsam/linear/SubgraphPreconditioner.h
+++ b/gtsam/linear/SubgraphPreconditioner.h
@@ -32,7 +32,6 @@
 #include <boost/serialization/nvp.hpp>
 #include <boost/shared_ptr.hpp>
 
-#include <sys/_types/_size_t.h>
 #include <map>
 #include <utility>
 #include <vector>