diff --git a/unsupported/Eigen/CXX11/src/Tensor/TensorIndexList.h b/unsupported/Eigen/CXX11/src/Tensor/TensorIndexList.h
index 2d8c7b9..3c55524 100644
--- a/unsupported/Eigen/CXX11/src/Tensor/TensorIndexList.h
+++ b/unsupported/Eigen/CXX11/src/Tensor/TensorIndexList.h
@@ -379,10 +379,10 @@
 };
 
 template<typename FirstType, typename... OtherTypes> struct array_size<IndexPairList<FirstType, OtherTypes...> > {
-  static const size_t value = std::tuple_size<std::tuple<FirstType, OtherTypes...> >::value;
+  static const size_t value = 1 + sizeof...(OtherTypes);
 };
 template<typename FirstType, typename... OtherTypes> struct array_size<const IndexPairList<FirstType, OtherTypes...> > {
-  static const size_t value = std::tuple_size<std::tuple<FirstType, OtherTypes...> >::value;
+  static const size_t value = 1 + sizeof...(OtherTypes);
 };
 
 template<Index N, typename FirstType, typename... OtherTypes> EIGEN_DEVICE_FUNC constexpr Index array_get(IndexList<FirstType, OtherTypes...>& a) {