diff --git a/python/gtsam/gtsam.tpl b/python/gtsam/gtsam.tpl
index 60b3d1fd0..26c220a8f 100644
--- a/python/gtsam/gtsam.tpl
+++ b/python/gtsam/gtsam.tpl
@@ -13,6 +13,7 @@
 #include <pybind11/eigen.h>
 #include <pybind11/stl_bind.h>
 #include <pybind11/pybind11.h>
+#include <pybind11/iostream.h>
 #include "gtsam/config.h"
 #include "gtsam/base/serialization.h"
 #include "gtsam/nonlinear/utilities.h"  // for RedirectCout.
diff --git a/python/gtsam_unstable/gtsam_unstable.tpl b/python/gtsam_unstable/gtsam_unstable.tpl
index 111e46d5e..356f37c42 100644
--- a/python/gtsam_unstable/gtsam_unstable.tpl
+++ b/python/gtsam_unstable/gtsam_unstable.tpl
@@ -13,6 +13,7 @@
 #include <pybind11/eigen.h>
 #include <pybind11/stl_bind.h>
 #include <pybind11/pybind11.h>
+#include <pybind11/iostream.h>
 #include "gtsam/base/serialization.h"
 #include "gtsam/nonlinear/utilities.h"  // for RedirectCout.