diff --git a/unsupported/Eigen/CXX11/src/Tensor/Tensor.h b/unsupported/Eigen/CXX11/src/Tensor/Tensor.h
index 57d44baf9..3ac465d24 100644
--- a/unsupported/Eigen/CXX11/src/Tensor/Tensor.h
+++ b/unsupported/Eigen/CXX11/src/Tensor/Tensor.h
@@ -91,7 +91,7 @@ class Tensor : public TensorBase<Tensor<Scalar_, NumIndices_, Options_, IndexTyp
 #ifdef EIGEN_HAS_SFINAE
     template<typename CustomIndices>
     struct isOfNormalIndex{
-      static const bool is_array = internal::is_base_of<array<Index, NumIndices>, CustomIndices >::value;
+      static const bool is_array = internal::is_base_of<array<Index, NumIndices>, CustomIndices>::value;
       static const bool is_int = NumTraits<CustomIndices>::IsInteger;
       static const bool value = is_array | is_int;
     };
@@ -120,11 +120,8 @@ class Tensor : public TensorBase<Tensor<Scalar_, NumIndices_, Options_, IndexTyp
       EIGEN_STATIC_ASSERT(sizeof...(otherIndices) + 2 == NumIndices, YOU_MADE_A_PROGRAMMING_MISTAKE)
       return coeff(array<Index, NumIndices>{{firstIndex, secondIndex, otherIndices...}});
     }
-
-
 #endif
 
-
     // normal indices
     EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE const Scalar& coeff(const array<Index, NumIndices>& indices) const
     {
@@ -137,7 +134,7 @@ class Tensor : public TensorBase<Tensor<Scalar_, NumIndices_, Options_, IndexTyp
     template<typename CustomIndices,
              EIGEN_SFINAE_ENABLE_IF( !(isOfNormalIndex<CustomIndices>::value) )
     >
-    EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE const Scalar& coeff(const CustomIndices & indices) const
+    EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE const Scalar& coeff(CustomIndices& indices) const
     {
         return coeff(internal::customIndices2Array<Index,NumIndices>(indices));
     }
@@ -171,7 +168,7 @@ class Tensor : public TensorBase<Tensor<Scalar_, NumIndices_, Options_, IndexTyp
     template<typename CustomIndices,
              EIGEN_SFINAE_ENABLE_IF( !(isOfNormalIndex<CustomIndices>::value) )
              >
-    EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE Scalar& coeffRef(const CustomIndices & indices)
+    EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE Scalar& coeffRef(CustomIndices& indices)
     {
         return coeffRef(internal::customIndices2Array<Index,NumIndices>(indices));
     }
@@ -219,7 +216,7 @@ class Tensor : public TensorBase<Tensor<Scalar_, NumIndices_, Options_, IndexTyp
     template<typename CustomIndices,
              EIGEN_SFINAE_ENABLE_IF( !(isOfNormalIndex<CustomIndices>::value) )
     >
-    EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE const Scalar& operator()(const CustomIndices & indices) const
+    EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE const Scalar& operator()(CustomIndices& indices) const
     {
         return coeff(internal::customIndices2Array<Index,NumIndices>(indices));
     }
@@ -286,7 +283,7 @@ class Tensor : public TensorBase<Tensor<Scalar_, NumIndices_, Options_, IndexTyp
     template<typename CustomIndices,
              EIGEN_SFINAE_ENABLE_IF( !(isOfNormalIndex<CustomIndices>::value) )
     >
-    EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE Scalar& operator()(const CustomIndices & indices)
+    EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE Scalar& operator()(CustomIndices& indices)
     {
       return coeffRef(internal::customIndices2Array<Index,NumIndices>(indices));
     }
@@ -441,9 +438,9 @@ class Tensor : public TensorBase<Tensor<Scalar_, NumIndices_, Options_, IndexTyp
     template<typename CustomDimension,
              EIGEN_SFINAE_ENABLE_IF( !(isOfNormalIndex<CustomDimension>::value) )
     >
-    EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE void resize(const CustomDimension & dimensions)
+    EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE void resize(CustomDimension& dimensions)
     {
-      return coeffRef(internal::customIndices2Array<Index,NumIndices>(dimensions));
+      resize(internal::customIndices2Array<Index,NumIndices>(dimensions));
     }
 #endif
 
diff --git a/unsupported/Eigen/CXX11/src/Tensor/TensorMeta.h b/unsupported/Eigen/CXX11/src/Tensor/TensorMeta.h
index d1efc1a87..07735fa5f 100644
--- a/unsupported/Eigen/CXX11/src/Tensor/TensorMeta.h
+++ b/unsupported/Eigen/CXX11/src/Tensor/TensorMeta.h
@@ -82,15 +82,15 @@ namespace internal{
 
   template<typename IndexType, Index... Is>
   EIGEN_CONSTEXPR EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE
-  array<Index,sizeof...(Is)> customIndices2Array(const IndexType & idx, numeric_list<Index,Is...>) {
-    return { idx(Is)... };
+  array<Index, sizeof...(Is)> customIndices2Array(IndexType& idx, numeric_list<Index, Is...>) {
+    return { idx[Is]... };
   }
 
   /** Make an array (for index/dimensions) out of a custom index */
   template<typename Index, int NumIndices, typename IndexType>
   EIGEN_CONSTEXPR EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE
-  array<Index,NumIndices> customIndices2Array(const IndexType & idx) {
-    return customIndices2Array(idx, typename gen_numeric_list<Index,NumIndices>::type{});
+  array<Index, NumIndices> customIndices2Array(IndexType& idx) {
+    return customIndices2Array(idx, typename gen_numeric_list<Index, NumIndices>::type{});
   }
 
 
diff --git a/unsupported/test/cxx11_tensor_custom_index.cpp b/unsupported/test/cxx11_tensor_custom_index.cpp
index ff9545a7a..4528cc176 100644
--- a/unsupported/test/cxx11_tensor_custom_index.cpp
+++ b/unsupported/test/cxx11_tensor_custom_index.cpp
@@ -9,6 +9,7 @@
 
 #include "main.h"
 #include <limits>
+#include <map>
 
 #include <Eigen/Dense>
 #include <Eigen/CXX11/Tensor>
@@ -17,22 +18,83 @@ using Eigen::Tensor;
 
 
 template <int DataLayout>
-static void test_custom_index() {
-
+static void test_map_as_index()
+{
+#ifdef EIGEN_HAS_SFINAE
   Tensor<float, 4, DataLayout> tensor(2, 3, 5, 7);
   tensor.setRandom();
 
   using NormalIndex = DSizes<ptrdiff_t, 4>;
-  using CustomIndex = Matrix<unsigned int , 4, 1>;
+  using CustomIndex = std::map<ptrdiff_t, ptrdiff_t>;
+  CustomIndex coeffC;
+  coeffC[0] = 1;
+  coeffC[1] = 2;
+  coeffC[2] = 4;
+  coeffC[3] = 1;
+  NormalIndex coeff(1,2,4,1);
+
+  VERIFY_IS_EQUAL(tensor.coeff(coeffC), tensor.coeff(coeff));
+  VERIFY_IS_EQUAL(tensor.coeffRef(coeffC), tensor.coeffRef(coeff));
+#endif
+}
+
+
+template <int DataLayout>
+static void test_matrix_as_index()
+{
+#ifdef EIGEN_HAS_SFINAE
+  Tensor<float, 4, DataLayout> tensor(2, 3, 5, 7);
+  tensor.setRandom();
+
+  using NormalIndex = DSizes<ptrdiff_t, 4>;
+  using CustomIndex = Matrix<unsigned int, 4, 1>;
   CustomIndex coeffC(1,2,4,1);
   NormalIndex coeff(1,2,4,1);
 
   VERIFY_IS_EQUAL(tensor.coeff(coeffC), tensor.coeff(coeff));
   VERIFY_IS_EQUAL(tensor.coeffRef(coeffC), tensor.coeffRef(coeff));
+#endif
+}
+
+
+template <int DataLayout>
+static void test_varlist_as_index()
+{
+#ifdef EIGEN_HAS_SFINAE
+  Tensor<float, 4, DataLayout> tensor(2, 3, 5, 7);
+  tensor.setRandom();
+
+  DSizes<ptrdiff_t, 4> coeff(1,2,4,1);
+
+  VERIFY_IS_EQUAL(tensor.coeff({1,2,4,1}), tensor.coeff(coeff));
+  VERIFY_IS_EQUAL(tensor.coeffRef({1,2,4,1}), tensor.coeffRef(coeff));
+#endif
+}
+
+
+template <int DataLayout>
+static void test_sizes_as_index()
+{
+#ifdef EIGEN_HAS_SFINAE
+  Tensor<float, 4, DataLayout> tensor(2, 3, 5, 7);
+  tensor.setRandom();
+
+  DSizes<ptrdiff_t, 4> coeff(1,2,4,1);
+  Sizes<1,2,4,1> coeffC;
+
+  VERIFY_IS_EQUAL(tensor.coeff(coeffC), tensor.coeff(coeff));
+  VERIFY_IS_EQUAL(tensor.coeffRef(coeffC), tensor.coeffRef(coeff));
+#endif
 }
 
 
 void test_cxx11_tensor_custom_index() {
-  test_custom_index<ColMajor>();
-  test_custom_index<RowMajor>();
+  test_map_as_index<ColMajor>();
+  test_map_as_index<RowMajor>();
+  test_matrix_as_index<ColMajor>();
+  test_matrix_as_index<RowMajor>();
+  test_varlist_as_index<ColMajor>();
+  test_varlist_as_index<RowMajor>();
+  test_sizes_as_index<ColMajor>();
+  test_sizes_as_index<RowMajor>();
 }
diff --git a/unsupported/test/cxx11_tensor_simple.cpp b/unsupported/test/cxx11_tensor_simple.cpp
index 8cd2ab7fd..0ce92eed9 100644
--- a/unsupported/test/cxx11_tensor_simple.cpp
+++ b/unsupported/test/cxx11_tensor_simple.cpp
@@ -293,7 +293,3 @@ void test_cxx11_tensor_simple()
   CALL_SUBTEST(test_simple_assign());
   CALL_SUBTEST(test_resize());
 }
-
-/*
- * kate: space-indent on; indent-width 2; mixedindent off; indent-mode cstyle;
- */