diff --git a/include/sparrow/dictionary_encoded_layout.hpp b/include/sparrow/dictionary_encoded_layout.hpp
index 674a4e9f..1f754427 100644
--- a/include/sparrow/dictionary_encoded_layout.hpp
+++ b/include/sparrow/dictionary_encoded_layout.hpp
@@ -34,7 +34,7 @@ namespace sparrow
     template <class IL, class SL, bool is_const>
     class dictionary_value_iterator : public iterator_base<
                                           dictionary_value_iterator<IL, SL, is_const>,
-                                          typename SL::const_reference,
+                                          typename SL::value_type,
                                           std::random_access_iterator_tag,
                                           typename SL::const_reference>
     {
@@ -43,7 +43,7 @@ namespace sparrow
         using self_type = dictionary_value_iterator<IL, SL, is_const>;
         using base_type = iterator_base<
             self_type,
-            typename SL::const_reference,
+            typename SL::value_type,
             std::random_access_iterator_tag,
             typename SL::const_reference>;
         using reference = typename base_type::reference;
@@ -57,7 +57,7 @@ namespace sparrow
         dictionary_value_iterator(index_iterator index_it, sub_layout_reference sub_layout_reference);
 
     private:
-        SL::const_reference dereference() const;
+        reference dereference() const;
         void increment();
         void decrement();
         void advance(difference_type n);
@@ -108,8 +108,8 @@ namespace sparrow
         using inner_reference = reference_proxy<SL>;
         using inner_const_reference = const_reference_proxy<SL>;
         using bitmap_type = array_data::bitmap_type;
-        using bitmap_const_reference = typename bitmap_type::const_reference;
-        using value_type = reference_proxy<SL>;
+        using bitmap_const_reference = bitmap_type::const_reference;
+        using value_type = SL::value_type;
         using reference = reference_proxy<SL>;
         using const_reference = const_reference_proxy<SL>;
         using size_type = std::size_t;
@@ -152,7 +152,7 @@ namespace sparrow
         const_value_range values() const;
 
     private:
-        const indexes_layout* get_const_indexes_layout() const;
+        const indexes_layout& get_const_indexes_layout() const;
 
         const_value_iterator value_cbegin() const;
         const_value_iterator value_cend() const;
@@ -189,7 +189,7 @@ namespace sparrow
     }
 
     template <class IL, class SL, bool is_const>
-    auto dictionary_value_iterator<IL, SL, is_const>::dereference() const -> SL::const_reference
+    auto dictionary_value_iterator<IL, SL, is_const>::dereference() const -> reference
     {
         assert(m_sub_layout_reference.has_value());
         return (*m_sub_layout_reference).get()[*m_index_it];
@@ -273,37 +273,37 @@ namespace sparrow
     template <std::integral T, class SL, layout_offset OT>
     auto dictionary_encoded_layout<T, SL, OT>::bitmap() const -> const_bitmap_range
     {
-        return get_const_indexes_layout()->bitmap();
+        return get_const_indexes_layout().bitmap();
     }
 
     template <std::integral T, class SL, layout_offset OT>
-    const typename dictionary_encoded_layout<T, SL, OT>::indexes_layout* dictionary_encoded_layout<T, SL, OT>::get_const_indexes_layout() const
+    const typename dictionary_encoded_layout<T, SL, OT>::indexes_layout& dictionary_encoded_layout<T, SL, OT>::get_const_indexes_layout() const
     {
-        return const_cast<const indexes_layout*>(m_indexes_layout.get());
+        return *const_cast<const indexes_layout*>(m_indexes_layout.get());
     }
 
     template <std::integral T, class SL, layout_offset OT>
     auto dictionary_encoded_layout<T, SL, OT>::cbegin() const -> const_iterator
     {
-        return const_iterator(value_cbegin(), get_const_indexes_layout()->bitmap().begin());
+        return const_iterator(value_cbegin(), get_const_indexes_layout().bitmap().begin());
     }
 
     template <std::integral T, class SL, layout_offset OT>
     auto dictionary_encoded_layout<T, SL, OT>::cend() const -> const_iterator
     {
-        return const_iterator(value_cend(), get_const_indexes_layout()->bitmap().end());
+        return const_iterator(value_cend(), get_const_indexes_layout().bitmap().end());
     }
 
     template <std::integral T, class SL, layout_offset OT>
     auto dictionary_encoded_layout<T, SL, OT>::value_cbegin() const -> const_value_iterator
     {
-        return const_value_iterator(get_const_indexes_layout()->values().begin(), *m_sub_layout);
+        return const_value_iterator(get_const_indexes_layout().values().begin(), *m_sub_layout);
     }
 
     template <std::integral T, class SL, layout_offset OT>
     auto dictionary_encoded_layout<T, SL, OT>::value_cend() const -> const_value_iterator
     {
-        return const_value_iterator(get_const_indexes_layout()->values().end(), *m_sub_layout);
+        return const_value_iterator(get_const_indexes_layout().values().end(), *m_sub_layout);
     }
 
     template <std::integral T, class SL, layout_offset OT>