diff --git a/gtsam/base/utilities.h b/gtsam/base/utilities.h
index d9b92b8aa..22e90d275 100644
--- a/gtsam/base/utilities.h
+++ b/gtsam/base/utilities.h
@@ -27,3 +27,41 @@ private:
 };
 
 }
+
+// boost::index_sequence was introduced in 1.66, so we'll manually define an
+// implementation if user has 1.65.  boost::index_sequence is used to get array
+// indices that align with a parameter pack.
+#if BOOST_VERSION >= 106600
+#include <boost/mp11/integer_sequence.hpp>
+#else
+namespace boost {
+namespace mp11 {
+// Adapted from https://stackoverflow.com/a/32223343/9151520
+template <size_t... Ints>
+struct index_sequence {
+  using type = index_sequence;
+  using value_type = size_t;
+  static constexpr std::size_t size() noexcept { return sizeof...(Ints); }
+};
+namespace detail {
+template <class Sequence1, class Sequence2>
+struct _merge_and_renumber;
+
+template <size_t... I1, size_t... I2>
+struct _merge_and_renumber<index_sequence<I1...>, index_sequence<I2...> >
+    : index_sequence<I1..., (sizeof...(I1) + I2)...> {};
+}  // namespace detail
+template <size_t N>
+struct make_index_sequence
+    : detail::_merge_and_renumber<
+          typename make_index_sequence<N / 2>::type,
+          typename make_index_sequence<N - N / 2>::type> {};
+template <>
+struct make_index_sequence<0> : index_sequence<> {};
+template <>
+struct make_index_sequence<1> : index_sequence<0> {};
+template <class... T>
+using index_sequence_for = make_index_sequence<sizeof...(T)>;
+}  // namespace mp11
+}  // namespace boost
+#endif
diff --git a/gtsam/nonlinear/NonlinearFactor.h b/gtsam/nonlinear/NonlinearFactor.h
index 212364af3..4deef0d3a 100644
--- a/gtsam/nonlinear/NonlinearFactor.h
+++ b/gtsam/nonlinear/NonlinearFactor.h
@@ -25,48 +25,11 @@
 #include <gtsam/linear/JacobianFactor.h>
 #include <gtsam/inference/Factor.h>
 #include <gtsam/base/OptionalJacobian.h>
+#include <gtsam/base/utilities.h>  // boost::index_sequence
 
 #include <boost/serialization/base_object.hpp>
 #include <boost/assign/list_of.hpp>
 
-// boost::index_sequence was introduced in 1.66, so we'll manually define an
-// implementation if user has 1.65.  boost::index_sequence is used to get array
-// indices that align with a parameter pack.
-#if BOOST_VERSION >= 106600
-#include <boost/mp11/integer_sequence.hpp>
-#else
-namespace boost {
-namespace mp11 {
-// Adapted from https://stackoverflow.com/a/32223343/9151520
-template <size_t... Ints>
-struct index_sequence {
-  using type = index_sequence;
-  using value_type = size_t;
-  static constexpr std::size_t size() noexcept { return sizeof...(Ints); }
-};
-namespace detail {
-template <class Sequence1, class Sequence2>
-struct _merge_and_renumber;
-
-template <size_t... I1, size_t... I2>
-struct _merge_and_renumber<index_sequence<I1...>, index_sequence<I2...> >
-    : index_sequence<I1..., (sizeof...(I1) + I2)...> {};
-}  // namespace detail
-template <size_t N>
-struct make_index_sequence
-    : detail::_merge_and_renumber<
-          typename make_index_sequence<N / 2>::type,
-          typename make_index_sequence<N - N / 2>::type> {};
-template <>
-struct make_index_sequence<0> : index_sequence<> {};
-template <>
-struct make_index_sequence<1> : index_sequence<0> {};
-template <class... T>
-using index_sequence_for = make_index_sequence<sizeof...(T)>;
-}  // namespace mp11
-}  // namespace boost
-#endif
-
 namespace gtsam {
 
 using boost::assign::cref_list_of;