diff --git a/unsupported/Eigen/CXX11/src/Tensor/Tensor.h b/unsupported/Eigen/CXX11/src/Tensor/Tensor.h
index 0df1345c2..6d357545c 100644
--- a/unsupported/Eigen/CXX11/src/Tensor/Tensor.h
+++ b/unsupported/Eigen/CXX11/src/Tensor/Tensor.h
@@ -59,7 +59,7 @@ namespace Eigen {
   * \ref TopicStorageOrders
   */
 
-template<typename Scalar_, std::size_t NumIndices_, int Options_, typename IndexType_>
+template<typename Scalar_, int NumIndices_, int Options_, typename IndexType_>
 class Tensor : public TensorBase<Tensor<Scalar_, NumIndices_, Options_, IndexType_> >
 {
   public:
@@ -82,7 +82,7 @@ class Tensor : public TensorBase<Tensor<Scalar_, NumIndices_, Options_, IndexTyp
     };
 
     static const int Options = Options_;
-    static const std::size_t NumIndices = NumIndices_;
+    static const int NumIndices = NumIndices_;
     typedef DSizes<Index, NumIndices_> Dimensions;
 
   protected:
@@ -433,7 +433,7 @@ class Tensor : public TensorBase<Tensor<Scalar_, NumIndices_, Options_, IndexTyp
     /** Normal Dimension */
     EIGEN_DEVICE_FUNC void resize(const array<Index, NumIndices>& dimensions)
     {
-      std::size_t i;
+      int i;
       Index size = Index(1);
       for (i = 0; i < NumIndices; i++) {
         internal::check_rows_cols_for_overflow<Dynamic>::run(size, dimensions[i]);
@@ -451,7 +451,7 @@ class Tensor : public TensorBase<Tensor<Scalar_, NumIndices_, Options_, IndexTyp
     // Why this overload, DSizes is derived from array ??? //
     EIGEN_DEVICE_FUNC void resize(const DSizes<Index, NumIndices>& dimensions) {
       array<Index, NumIndices> dims;
-      for (std::size_t i = 0; i < NumIndices; ++i) {
+      for (int i = 0; i < NumIndices; ++i) {
         dims[i] = dimensions[i];
       }
       resize(dims);
@@ -480,7 +480,7 @@ class Tensor : public TensorBase<Tensor<Scalar_, NumIndices_, Options_, IndexTyp
     EIGEN_DEVICE_FUNC
     void resize(const Sizes<Indices...>& dimensions) {
       array<Index, NumIndices> dims;
-      for (std::size_t i = 0; i < NumIndices; ++i) {
+      for (int i = 0; i < NumIndices; ++i) {
         dims[i] = static_cast<Index>(dimensions[i]);
       }
       resize(dims);
@@ -490,7 +490,7 @@ class Tensor : public TensorBase<Tensor<Scalar_, NumIndices_, Options_, IndexTyp
     EIGEN_DEVICE_FUNC
     void resize(const Sizes<V1, V2, V3, V4, V5>& dimensions) {
       array<Index, NumIndices> dims;
-      for (std::size_t i = 0; i < NumIndices; ++i) {
+      for (int i = 0; i < NumIndices; ++i) {
         dims[i] = static_cast<Index>(dimensions[i]);
       }
       resize(dims);
diff --git a/unsupported/Eigen/CXX11/src/Tensor/TensorBase.h b/unsupported/Eigen/CXX11/src/Tensor/TensorBase.h
index 5ec1deaf8..d1ce3d0ed 100644
--- a/unsupported/Eigen/CXX11/src/Tensor/TensorBase.h
+++ b/unsupported/Eigen/CXX11/src/Tensor/TensorBase.h
@@ -638,8 +638,8 @@ class TensorBase<Derived, ReadOnlyAccessors>
     }
 
   protected:
-    template <typename Scalar, std::size_t NumIndices, int Options, typename IndexType> friend class Tensor;
-   template <typename Scalar, typename Dimensions, int Option, typename IndexTypes> friend class TensorFixedSize;
+    template <typename Scalar, int NumIndices, int Options, typename IndexType> friend class Tensor;
+    template <typename Scalar, typename Dimensions, int Option, typename IndexTypes> friend class TensorFixedSize;
     template <typename OtherDerived, int AccessLevel> friend class TensorBase;
     EIGEN_DEVICE_FUNC
     EIGEN_STRONG_INLINE const Derived& derived() const { return *static_cast<const Derived*>(this); }
@@ -655,7 +655,7 @@ class TensorBase<Derived, WriteAccessors> : public TensorBase<Derived, ReadOnlyA
     typedef typename internal::packet_traits<Scalar>::type PacketReturnType;
     static const int NumDimensions = DerivedTraits::NumDimensions;
 
-    template <typename Scalar, std::size_t NumIndices, int Options, typename IndexType> friend class Tensor;
+    template <typename Scalar, int NumIndices, int Options, typename IndexType> friend class Tensor;
     template <typename Scalar, typename Dimensions, int Option, typename IndexTypes> friend class TensorFixedSize;
     template <typename OtherDerived, int AccessLevel> friend class TensorBase;
 
diff --git a/unsupported/Eigen/CXX11/src/Tensor/TensorForwardDeclarations.h b/unsupported/Eigen/CXX11/src/Tensor/TensorForwardDeclarations.h
index fbeb9c59a..a8bd8b888 100644
--- a/unsupported/Eigen/CXX11/src/Tensor/TensorForwardDeclarations.h
+++ b/unsupported/Eigen/CXX11/src/Tensor/TensorForwardDeclarations.h
@@ -12,7 +12,7 @@
 
 namespace Eigen {
 
-template<typename Scalar_, std::size_t NumIndices_, int Options_ = 0, typename IndexType = DenseIndex> class Tensor;
+template<typename Scalar_, int NumIndices_, int Options_ = 0, typename IndexType = DenseIndex> class Tensor;
 template<typename Scalar_, typename Dimensions, int Options_ = 0, typename IndexType = DenseIndex> class TensorFixedSize;
 template<typename PlainObjectType, int Options_ = Unaligned> class TensorMap;
 template<typename PlainObjectType> class TensorRef;
diff --git a/unsupported/Eigen/CXX11/src/Tensor/TensorTraits.h b/unsupported/Eigen/CXX11/src/Tensor/TensorTraits.h
index 8f1c02ea4..7a9568b36 100644
--- a/unsupported/Eigen/CXX11/src/Tensor/TensorTraits.h
+++ b/unsupported/Eigen/CXX11/src/Tensor/TensorTraits.h
@@ -44,7 +44,7 @@ class compute_tensor_flags
 };
 
 
-template<typename Scalar_, std::size_t NumIndices_, int Options_, typename IndexType_>
+template<typename Scalar_, int NumIndices_, int Options_, typename IndexType_>
 struct traits<Tensor<Scalar_, NumIndices_, Options_, IndexType_> >
 {
   typedef Scalar_ Scalar;
@@ -107,13 +107,13 @@ struct traits<TensorRef<PlainObjectType> >
 };
 
 
-template<typename _Scalar, std::size_t NumIndices_, int Options, typename IndexType_>
+template<typename _Scalar, int NumIndices_, int Options, typename IndexType_>
 struct eval<Tensor<_Scalar, NumIndices_, Options, IndexType_>, Eigen::Dense>
 {
   typedef const Tensor<_Scalar, NumIndices_, Options, IndexType_>& type;
 };
 
-template<typename _Scalar, std::size_t NumIndices_, int Options, typename IndexType_>
+template<typename _Scalar, int NumIndices_, int Options, typename IndexType_>
 struct eval<const Tensor<_Scalar, NumIndices_, Options, IndexType_>, Eigen::Dense>
 {
   typedef const Tensor<_Scalar, NumIndices_, Options, IndexType_>& type;
@@ -161,13 +161,13 @@ template<typename T, int n=1, typename PlainObject = void> struct nested
   typedef typename ref_selector<T>::type type;
 };
 
-template <typename Scalar_, std::size_t NumIndices_, int Options_, typename IndexType_>
+template <typename Scalar_, int NumIndices_, int Options_, typename IndexType_>
 struct nested<Tensor<Scalar_, NumIndices_, Options_, IndexType_> >
 {
   typedef const Tensor<Scalar_, NumIndices_, Options_, IndexType_>& type;
 };
 
-template <typename Scalar_, std::size_t NumIndices_, int Options_, typename IndexType_>
+template <typename Scalar_, int NumIndices_, int Options_, typename IndexType_>
 struct nested<const Tensor<Scalar_, NumIndices_, Options_, IndexType_> >
 {
   typedef const Tensor<Scalar_, NumIndices_, Options_, IndexType_>& type;