diff --git a/include/rotgen/container/block/dynamic.hpp b/include/rotgen/container/block/dynamic.hpp
index f452f46..9ed70b2 100644
--- a/include/rotgen/container/block/dynamic.hpp
+++ b/include/rotgen/container/block/dynamic.hpp
@@ -87,62 +87,52 @@ namespace rotgen
       return *this;
     }
 
-    block(Ref const& r,
-          std::size_t i0,
-          std::size_t j0,
-          std::size_t ni,
-          std::size_t nj)
+    block(Ref const& r, Index i0, Index j0, Index ni, Index nj)
     requires(!requires { typename Ref::rotgen_block_tag; } && is_immutable)
       : parent(r.base(), i0, j0, ni, nj)
     {
     }
 
-    block(Ref const& r,
-          std::size_t i0,
-          std::size_t j0,
-          std::size_t ni,
-          std::size_t nj)
+    block(Ref const& r, Index i0, Index j0, Index ni, Index nj)
     requires(requires { typename Ref::rotgen_block_tag; } && is_immutable)
       : parent(r.base(), i0, j0, ni, nj)
     {
     }
 
-    block(Ref const& r, std::size_t i0, std::size_t j0)
+    block(Ref const& r, Index i0, Index j0)
     requires(!requires { typename Ref::rotgen_block_tag; } && Rows != -1 &&
              Cols != -1 && is_immutable)
       : parent(r.base(), i0, j0, Rows, Cols)
     {
     }
 
-    block(Ref const& r, std::size_t i0, std::size_t j0)
+    block(Ref const& r, Index i0, Index j0)
     requires(requires { typename Ref::rotgen_block_tag; } && Rows != -1 &&
              Cols != -1 && is_immutable)
       : parent(r.base(), i0, j0, Rows, Cols)
     {
     }
 
-    block(
-      Ref& r, std::size_t i0, std::size_t j0, std::size_t ni, std::size_t nj)
+    block(Ref& r, Index i0, Index j0, Index ni, Index nj)
     requires(!requires { typename Ref::rotgen_block_tag; } && !is_immutable)
       : parent(r.base(), i0, j0, ni, nj)
     {
     }
 
-    block(
-      Ref& r, std::size_t i0, std::size_t j0, std::size_t ni, std::size_t nj)
+    block(Ref& r, Index i0, Index j0, Index ni, Index nj)
     requires(requires { typename Ref::rotgen_block_tag; } && !is_immutable)
       : parent(r.base(), i0, j0, ni, nj)
     {
     }
 
-    block(Ref& r, std::size_t i0, std::size_t j0)
+    block(Ref& r, Index i0, Index j0)
     requires(!requires { typename Ref::rotgen_block_tag; } && Rows != -1 &&
              Cols != -1 && !is_immutable)
       : parent(r.base(), i0, j0, Rows, Cols)
     {
     }
 
-    block(Ref& r, std::size_t i0, std::size_t j0)
+    block(Ref& r, Index i0, Index j0)
     requires(requires { typename Ref::rotgen_block_tag; } && Rows != -1 &&
              Cols != -1 && !is_immutable)
       : parent(r.base(), i0, j0, Rows, Cols)
diff --git a/include/rotgen/container/block/fixed.hpp b/include/rotgen/container/block/fixed.hpp
index e9ab4a2..df4d148 100644
--- a/include/rotgen/container/block/fixed.hpp
+++ b/include/rotgen/container/block/fixed.hpp
@@ -109,30 +109,25 @@ namespace rotgen
     block& operator=(block const&) = default;
     block& operator=(block&&) = default;
 
-    block(Ref const& r,
-          std::size_t i0,
-          std::size_t j0,
-          std::size_t ni,
-          std::size_t nj)
+    block(Ref const& r, Index i0, Index j0, Index ni, Index nj)
     requires(is_immutable)
       : parent(r.base(), i0, j0, ni, nj)
     {
     }
 
-    block(Ref const& r, std::size_t i0, std::size_t j0)
+    block(Ref const& r, Index i0, Index j0)
     requires(Rows != -1 && Cols != -1 && is_immutable)
       : parent(r.base(), i0, j0, Rows, Cols)
     {
     }
 
-    block(
-      Ref& r, std::size_t i0, std::size_t j0, std::size_t ni, std::size_t nj)
+    block(Ref& r, Index i0, Index j0, Index ni, Index nj)
     requires(!is_immutable)
       : parent(r.base(), i0, j0, ni, nj)
     {
     }
 
-    block(Ref& r, std::size_t i0, std::size_t j0)
+    block(Ref& r, Index i0, Index j0)
     requires(Rows != -1 && Cols != -1 && !is_immutable)
       : parent(r.base(), i0, j0, Rows, Cols)
     {
diff --git a/include/rotgen/container/matrix/dynamic.hpp b/include/rotgen/container/matrix/dynamic.hpp
index 697d177..8c96261 100644
--- a/include/rotgen/container/matrix/dynamic.hpp
+++ b/include/rotgen/container/matrix/dynamic.hpp
@@ -94,7 +94,7 @@ namespace rotgen
                "Mismatched between dynamic and static row size");
       if constexpr (Cols != -1)
       {
-        [[maybe_unused]] std::size_t c = 0;
+        [[maybe_unused]] Index c = 0;
         if (init.size()) c = init.begin()->size();
         assert(c == Cols &&
                "Mismatched between dynamic and static column size");
diff --git a/include/rotgen/container/matrix/dynamic/model.hpp b/include/rotgen/container/matrix/dynamic/model.hpp
index 6e1f153..2520239 100644
--- a/include/rotgen/container/matrix/dynamic/model.hpp
+++ b/include/rotgen/container/matrix/dynamic/model.hpp
@@ -15,10 +15,8 @@ class ROTGEN_EXPORT CLASSNAME
 {
 public:
   CLASSNAME();
-  CLASSNAME(std::size_t rows, std::size_t cols);
-  CLASSNAME(std::size_t rows,
-            std::size_t cols,
-            std::initializer_list<TYPE> init);
+  CLASSNAME(Index rows, Index cols);
+  CLASSNAME(Index rows, Index cols, std::initializer_list<TYPE> init);
 
   CLASSNAME(std::initializer_list<std::initializer_list<TYPE>> init);
 
@@ -34,8 +32,8 @@ public:
   Index cols() const;
   Index size() const;
 
-  void resize(std::size_t new_rows, std::size_t new_cols);
-  void conservativeResize(std::size_t new_rows, std::size_t new_cols);
+  void resize(Index new_rows, Index new_cols);
+  void conservativeResize(Index new_rows, Index new_cols);
 
   CLASSNAME normalized() const;
   CLASSNAME transpose() const;
@@ -64,11 +62,11 @@ public:
   TYPE norm() const;
   TYPE lp_norm(int p) const;
 
-  TYPE& operator()(std::size_t i, std::size_t j);
-  TYPE const& operator()(std::size_t i, std::size_t j) const;
+  TYPE& operator()(Index i, Index j);
+  TYPE const& operator()(Index i, Index j) const;
 
-  TYPE& operator()(std::size_t index);
-  TYPE const& operator()(std::size_t index) const;
+  TYPE& operator()(Index index);
+  TYPE const& operator()(Index index) const;
 
   CLASSNAME& operator+=(CLASSNAME const& rhs);
   CLASSNAME& operator-=(CLASSNAME const& rhs);
@@ -89,17 +87,17 @@ public:
   const TYPE* data() const;
   TYPE* data();
 
-  static CLASSNAME Zero(std::size_t rows, std::size_t cols);
-  static CLASSNAME Ones(std::size_t rows, std::size_t cols);
-  static CLASSNAME Constant(std::size_t rows, std::size_t cols, TYPE value);
-  static CLASSNAME Random(std::size_t rows, std::size_t cols);
-  static CLASSNAME Identity(std::size_t rows, std::size_t cols);
+  static CLASSNAME Zero(Index rows, Index cols);
+  static CLASSNAME Ones(Index rows, Index cols);
+  static CLASSNAME Constant(Index rows, Index cols, TYPE value);
+  static CLASSNAME Random(Index rows, Index cols);
+  static CLASSNAME Identity(Index rows, Index cols);
 
-  void setOnes(std::size_t rows, std::size_t cols);
-  void setZero(std::size_t rows, std::size_t cols);
-  void setConstant(std::size_t rows, std::size_t cols, TYPE value);
-  void setRandom(std::size_t rows, std::size_t cols);
-  void setIdentity(std::size_t rows, std::size_t cols);
+  void setOnes(Index rows, Index cols);
+  void setZero(Index rows, Index cols);
+  void setConstant(Index rows, Index cols, TYPE value);
+  void setRandom(Index rows, Index cols);
+  void setIdentity(Index rows, Index cols);
 
 private:
   struct payload;
diff --git a/include/rotgen/container/ref/dynamic.hpp b/include/rotgen/container/ref/dynamic.hpp
index fcd3d17..015e587 100644
--- a/include/rotgen/container/ref/dynamic.hpp
+++ b/include/rotgen/container/ref/dynamic.hpp
@@ -86,6 +86,45 @@ namespace rotgen
     using parent::cwiseInverse;
     using parent::cwiseSqrt;
 
+    // Compound Operators
+    template<typename A, int O, typename S>
+    ref& operator+=(ref<A, O, S> rhs)
+    requires(!is_immutable)
+    {
+      base() += rhs.base();
+      return *this;
+    }
+
+    template<typename A, int O, typename S>
+    ref& operator-=(ref<A, O, S> rhs)
+    requires(!is_immutable)
+    {
+      base() -= rhs.base();
+      return *this;
+    }
+
+    template<typename A, int O, typename S>
+    ref& operator*=(ref<A, O, S> rhs)
+    requires(!is_immutable)
+    {
+      base() *= rhs.base();
+      return *this;
+    }
+
+    ref& operator*=(std::convertible_to<value_type> auto s)
+    requires(!is_immutable)
+    {
+      base() *= s;
+      return *this;
+    }
+
+    ref& operator/=(std::convertible_to<value_type> auto s)
+    requires(!is_immutable)
+    {
+      base() /= s;
+      return *this;
+    }
+
     // Shape modifications
     using parent::adjoint;
     using parent::conjugate;
diff --git a/include/rotgen/container/ref/fixed.hpp b/include/rotgen/container/ref/fixed.hpp
index 039e700..3d5521d 100644
--- a/include/rotgen/container/ref/fixed.hpp
+++ b/include/rotgen/container/ref/fixed.hpp
@@ -132,6 +132,45 @@ namespace rotgen
     using parent::sum;
     using parent::trace;
 
+    // Compound Operators
+    template<typename A, int O, typename S>
+    ref& operator+=(ref<A, O, S> rhs)
+    requires(!is_immutable)
+    {
+      base() += rhs.base();
+      return *this;
+    }
+
+    template<typename A, int O, typename S>
+    ref& operator-=(ref<A, O, S> rhs)
+    requires(!is_immutable)
+    {
+      base() -= rhs.base();
+      return *this;
+    }
+
+    template<typename A, int O, typename S>
+    ref& operator*=(ref<A, O, S> rhs)
+    requires(!is_immutable)
+    {
+      base() *= rhs.base();
+      return *this;
+    }
+
+    ref& operator*=(std::convertible_to<value_type> auto s)
+    requires(!is_immutable)
+    {
+      base() *= s;
+      return *this;
+    }
+
+    ref& operator/=(std::convertible_to<value_type> auto s)
+    requires(!is_immutable)
+    {
+      base() /= s;
+      return *this;
+    }
+
     // Shape modifications
     using parent::adjoint;
     using parent::conjugate;
diff --git a/include/rotgen/container/ref/functions.hpp b/include/rotgen/container/ref/functions.hpp
index 732b95c..4fa278d 100644
--- a/include/rotgen/container/ref/functions.hpp
+++ b/include/rotgen/container/ref/functions.hpp
@@ -23,35 +23,6 @@ namespace rotgen
     return lhs.base() != rhs.base();
   }
 
-  template<typename A, int O, typename S, typename B, int P, typename T>
-  auto operator+=(ref<A, O, S> lhs, ref<B, P, T> rhs)
-  {
-    lhs.base() += rhs.base();
-    return lhs;
-  }
-
-  template<typename A, int O, typename S, typename B, int P, typename T>
-  auto operator-=(ref<A, O, S> lhs, ref<B, P, T> rhs)
-  {
-    lhs.base() -= rhs.base();
-    return lhs;
-  }
-
-  template<typename A, int O, typename S, typename B, int P, typename T>
-  auto operator*=(ref<A, O, S> lhs, ref<B, P, T> rhs)
-  {
-    lhs.base() *= rhs.base();
-    return lhs;
-  }
-
-  template<typename A, int O, typename S, typename B, int P, typename T>
-  auto operator/=(ref<A, O, S> lhs,
-                  std::convertible_to<typename A::value_type> auto s)
-  {
-    lhs.base() /= s;
-    return lhs;
-  }
-
   template<typename A, int O, typename S>
   auto operator*(std::convertible_to<typename A::value_type> auto s,
                  ref<A, O, S> rhs)
diff --git a/include/rotgen/detail/payload/matrix.hpp b/include/rotgen/detail/payload/matrix.hpp
index d10f755..b7d7a9d 100644
--- a/include/rotgen/detail/payload/matrix.hpp
+++ b/include/rotgen/detail/payload/matrix.hpp
@@ -26,7 +26,7 @@ namespace rotgen
 
     data_type data;
 
-    payload(std::size_t r = 0, std::size_t c = 0) : data(r, c) {}
+    payload(Index r = 0, Index c = 0) : data(r, c) {}
 
     payload(std::initializer_list<std::initializer_list<double>> init)
       : data(init)
@@ -49,7 +49,7 @@ namespace rotgen
 
     data_type data;
 
-    payload(std::size_t r = 0, std::size_t c = 0) : data(r, c) {}
+    payload(Index r = 0, Index c = 0) : data(r, c) {}
 
     payload(std::initializer_list<std::initializer_list<double>> init)
       : data(init)
@@ -72,7 +72,7 @@ namespace rotgen
 
     data_type data;
 
-    payload(std::size_t r = 0, std::size_t c = 0) : data(r, c) {}
+    payload(Index r = 0, Index c = 0) : data(r, c) {}
 
     payload(std::initializer_list<std::initializer_list<float>> init)
       : data(init)
@@ -95,7 +95,7 @@ namespace rotgen
 
     data_type data;
 
-    payload(std::size_t r = 0, std::size_t c = 0) : data(r, c) {}
+    payload(Index r = 0, Index c = 0) : data(r, c) {}
 
     payload(std::initializer_list<std::initializer_list<float>> init)
       : data(init)
diff --git a/include/rotgen/functions/functions.hpp b/include/rotgen/functions/functions.hpp
index 6ec88d4..7733f2d 100644
--- a/include/rotgen/functions/functions.hpp
+++ b/include/rotgen/functions/functions.hpp
@@ -14,19 +14,19 @@ namespace rotgen
   //-----------------------------------------------------------------------------------------------
   // Infos & Shape
   //-----------------------------------------------------------------------------------------------
-  std::size_t rows(auto const& m)
+  Index rows(auto const& m)
   requires(requires { m.rows(); })
   {
     return m.rows();
   }
 
-  std::size_t cols(auto const& m)
+  Index cols(auto const& m)
   requires(requires { m.cols(); })
   {
     return m.cols();
   }
 
-  std::size_t size(auto const& m)
+  Index size(auto const& m)
   requires(requires { m.size(); })
   {
     return m.size();
diff --git a/include/rotgen/functions/operators.hpp b/include/rotgen/functions/operators.hpp
index 7147e5d..e56fb82 100644
--- a/include/rotgen/functions/operators.hpp
+++ b/include/rotgen/functions/operators.hpp
@@ -8,6 +8,7 @@
 #pragma once
 
 #include <rotgen/concepts.hpp>
+
 #include <cassert>
 #include <iosfwd>
 
@@ -81,7 +82,7 @@ namespace rotgen
   // Compounds operators across types
   template<typename A, typename B>
   auto operator+=(A& a, B const& b)
-  requires(concepts::entity<A> || concepts::entity<B>)
+  requires(concepts::entity<A> && concepts::entity<B>)
   {
     if constexpr (!use_expression_templates)
       return generalize_t<A>(a) += generalize_t<B const>(b);
@@ -90,7 +91,7 @@ namespace rotgen
 
   template<typename A, typename B>
   auto operator-=(A& a, B const& b)
-  requires(concepts::entity<A> || concepts::entity<B>)
+  requires(concepts::entity<A> && concepts::entity<B>)
   {
     if constexpr (!use_expression_templates)
       return generalize_t<A>(a) -= generalize_t<B const>(b);
@@ -99,7 +100,7 @@ namespace rotgen
 
   template<typename A, typename B>
   auto operator*=(A& a, B const& b)
-  requires(concepts::entity<A> || concepts::entity<B>)
+  requires(concepts::entity<A> && concepts::entity<B>)
   {
     if constexpr (!use_expression_templates)
       return generalize_t<A>(a) *= generalize_t<B const>(b);
diff --git a/src/matrix/model.cpp b/src/matrix/model.cpp
index dcd0267..937e6d9 100644
--- a/src/matrix/model.cpp
+++ b/src/matrix/model.cpp
@@ -17,7 +17,7 @@
 //==================================================================================================
 CLASSNAME::CLASSNAME() : storage_(std::make_unique<payload>(0, 0)) {}
 
-CLASSNAME::CLASSNAME(std::size_t r, std::size_t c)
+CLASSNAME::CLASSNAME(Index r, Index c)
   : storage_(std::make_unique<payload>(r, c))
 {
 }
@@ -27,9 +27,7 @@ CLASSNAME::CLASSNAME(std::initializer_list<std::initializer_list<TYPE>> init)
 {
 }
 
-CLASSNAME::CLASSNAME(std::size_t r,
-                     std::size_t c,
-                     std::initializer_list<TYPE> init)
+CLASSNAME::CLASSNAME(Index r, Index c, std::initializer_list<TYPE> init)
   : CLASSNAME(r, c)
 {
   auto first = init.begin();
@@ -71,32 +69,32 @@ rotgen::Index CLASSNAME::size() const
   return storage_->data.size();
 }
 
-void CLASSNAME::resize(std::size_t new_rows, std::size_t new_cols)
+void CLASSNAME::resize(Index new_rows, Index new_cols)
 {
   storage_->data.resize(new_rows, new_cols);
 }
 
-void CLASSNAME::conservativeResize(std::size_t new_rows, std::size_t new_cols)
+void CLASSNAME::conservativeResize(Index new_rows, Index new_cols)
 {
   storage_->data.conservativeResize(new_rows, new_cols);
 }
 
-TYPE& CLASSNAME::operator()(std::size_t i, std::size_t j)
+TYPE& CLASSNAME::operator()(Index i, Index j)
 {
   return storage_->data(i, j);
 }
 
-TYPE const& CLASSNAME::operator()(std::size_t i, std::size_t j) const
+TYPE const& CLASSNAME::operator()(Index i, Index j) const
 {
   return storage_->data(i, j);
 }
 
-TYPE& CLASSNAME::operator()(std::size_t index)
+TYPE& CLASSNAME::operator()(Index index)
 {
   return storage_->data(index);
 }
 
-TYPE const& CLASSNAME::operator()(std::size_t index) const
+TYPE const& CLASSNAME::operator()(Index index) const
 {
   return storage_->data(index);
 }
@@ -303,27 +301,27 @@ CLASSNAME& CLASSNAME::operator/=(TYPE s)
 //==============================================================================
 // Generators functions
 //==============================================================================
-void CLASSNAME::setOnes(std::size_t rows, std::size_t cols)
+void CLASSNAME::setOnes(Index rows, Index cols)
 {
   storage_->assign(payload::data_type::Ones(rows, cols).eval());
 }
 
-void CLASSNAME::setZero(std::size_t rows, std::size_t cols)
+void CLASSNAME::setZero(Index rows, Index cols)
 {
   storage_->assign(payload::data_type::Zero(rows, cols).eval());
 }
 
-void CLASSNAME::setConstant(std::size_t rows, std::size_t cols, TYPE value)
+void CLASSNAME::setConstant(Index rows, Index cols, TYPE value)
 {
   storage_->assign(payload::data_type::Constant(rows, cols, value).eval());
 }
 
-void CLASSNAME::setRandom(std::size_t rows, std::size_t cols)
+void CLASSNAME::setRandom(Index rows, Index cols)
 {
   storage_->assign(payload::data_type::Random(rows, cols).eval());
 }
 
-void CLASSNAME::setIdentity(std::size_t rows, std::size_t cols)
+void CLASSNAME::setIdentity(Index rows, Index cols)
 {
   storage_->assign(payload::data_type::Identity(rows, cols).eval());
 }
@@ -331,21 +329,21 @@ void CLASSNAME::setIdentity(std::size_t rows, std::size_t cols)
 //==============================================================================
 // Static functions
 //==============================================================================
-CLASSNAME CLASSNAME::Ones(std::size_t rows, std::size_t cols)
+CLASSNAME CLASSNAME::Ones(Index rows, Index cols)
 {
   CLASSNAME m;
   m.storage_ = std::make_unique<payload>(payload::data_type::Ones(rows, cols));
   return m;
 }
 
-CLASSNAME CLASSNAME::Zero(std::size_t rows, std::size_t cols)
+CLASSNAME CLASSNAME::Zero(Index rows, Index cols)
 {
   CLASSNAME m;
   m.storage_ = std::make_unique<payload>(payload::data_type::Zero(rows, cols));
   return m;
 }
 
-CLASSNAME CLASSNAME::Constant(std::size_t rows, std::size_t cols, TYPE value)
+CLASSNAME CLASSNAME::Constant(Index rows, Index cols, TYPE value)
 {
   CLASSNAME m;
   m.storage_ =
@@ -353,7 +351,7 @@ CLASSNAME CLASSNAME::Constant(std::size_t rows, std::size_t cols, TYPE value)
   return m;
 }
 
-CLASSNAME CLASSNAME::Random(std::size_t rows, std::size_t cols)
+CLASSNAME CLASSNAME::Random(Index rows, Index cols)
 {
   CLASSNAME m;
   m.storage_ =
@@ -361,7 +359,7 @@ CLASSNAME CLASSNAME::Random(std::size_t rows, std::size_t cols)
   return m;
 }
 
-CLASSNAME CLASSNAME::Identity(std::size_t rows, std::size_t cols)
+CLASSNAME CLASSNAME::Identity(Index rows, Index cols)
 {
   CLASSNAME m;
   m.storage_ =
diff --git a/test/unit/functions/size_related.cpp b/test/unit/functions/size_related.cpp
index 3fb4f6e..7d87f5b 100644
--- a/test/unit/functions/size_related.cpp
+++ b/test/unit/functions/size_related.cpp
@@ -5,10 +5,11 @@
   SPDX-License-Identifier: BSL-1.0
 */
 //==================================================================================================
-#include "unit/tests.hpp"
 #include <rotgen/rotgen.hpp>
-#include <functional>
+
+#include "unit/tests.hpp"
 #include <array>
+#include <functional>
 
 template<typename MatrixType> struct MatrixDescriptor
 {
@@ -18,15 +19,15 @@ template<typename MatrixType> struct MatrixDescriptor
 
 template<typename MatrixType, std::size_t N>
 void test_matrix_sizes(
-  std::size_t rows,
-  std::size_t cols,
+  rotgen::Index rows,
+  rotgen::Index cols,
   std::function<void(MatrixType&, std::size_t, std::size_t)> const& init_fn,
   std::array<std::pair<int, int>, N> const& resize_dimensions)
 {
   MatrixType matrix(rows, cols);
 
-  for (std::size_t r = 0; r < rows; ++r)
-    for (std::size_t c = 0; c < cols; ++c) init_fn(matrix, r, c);
+  for (rotgen::Index r = 0; r < rows; ++r)
+    for (rotgen::Index c = 0; c < cols; ++c) init_fn(matrix, r, c);
 
   TTS_EQUAL(rotgen::size(matrix), rows * cols);
 
@@ -37,24 +38,24 @@ void test_matrix_sizes(
 
     rotgen::resize(matrix, r, c);
 
-    TTS_EQUAL(rotgen::rows(matrix), static_cast<size_t>(r));
-    TTS_EQUAL(rotgen::cols(matrix), static_cast<size_t>(c));
-    TTS_EQUAL(rotgen::size(matrix), static_cast<size_t>(r * c));
+    TTS_EQUAL(rotgen::rows(matrix), r);
+    TTS_EQUAL(rotgen::cols(matrix), c);
+    TTS_EQUAL(rotgen::size(matrix), r * c);
   }
 
   rotgen::conservativeResize(matrix, rows, cols);
   TTS_EQUAL(rotgen::size(matrix), rows * cols);
 
   int i = 1;
-  for (std::size_t r = 0; r < rows; ++r)
-    for (std::size_t c = 0; c < cols; ++c) matrix(r, c) = i++;
+  for (rotgen::Index r = 0; r < rows; ++r)
+    for (rotgen::Index c = 0; c < cols; ++c) matrix(r, c) = i++;
 
   rotgen::conservativeResize(matrix, rows + 3, cols + 2);
   TTS_EQUAL(rotgen::size(matrix), (rows + 3) * (cols + 2));
 
   i = 1;
-  for (std::size_t r = 0; r < rows; ++r)
-    for (std::size_t c = 0; c < cols; ++c) TTS_EQUAL(matrix(r, c), i++);
+  for (rotgen::Index r = 0; r < rows; ++r)
+    for (rotgen::Index c = 0; c < cols; ++c) TTS_EQUAL(matrix(r, c), i++);
 }
 
 TTS_CASE("Matrix size-related operations")