diff --git a/src/Collections/Dictionary.hpp b/src/Collections/Dictionary.hpp
index e7b8e6f..13ea997 100644
--- a/src/Collections/Dictionary.hpp
+++ b/src/Collections/Dictionary.hpp
@@ -1,5 +1,6 @@
 #ifndef ARBUTILS_DICTIONARY_HPP
 #define ARBUTILS_DICTIONARY_HPP
+#include <cstdint>
 #include <unordered_map>
 #include "../Assert.hpp"
 
@@ -20,7 +21,7 @@ namespace Arbutils::Collections {
         }
 
         inline void Insert(const KeyT& key, const ValueT& value) {
-            [[maybe_unused]] auto v = _map.insert({key, value});
+            [[maybe_unused]] const auto& v = _map.insert({key, value});
 #ifndef NO_ASSERT
             if (!v.second)
                 throw std::logic_error("Key already exists");
@@ -32,7 +33,7 @@ namespace Arbutils::Collections {
 
         [[nodiscard]] inline ValueT& Get(const KeyT& key) {
 #ifndef NO_ASSERT
-            auto find = _map.find(key);
+            const auto& find = _map.find(key);
             if (find == _map.end()) {
                 throw std::logic_error("Key not found");
             }
@@ -44,7 +45,7 @@ namespace Arbutils::Collections {
 
         [[nodiscard]] inline const ValueT& Get(const KeyT& key) const {
 #ifndef NO_ASSERT
-            auto find = _map.find(key);
+            const auto& find = _map.find(key);
             if (find == _map.end()) {
                 throw std::logic_error("Key not found");
             }
@@ -55,7 +56,7 @@ namespace Arbutils::Collections {
         }
 
         inline bool TryGet(const KeyT& key, ValueT& out) const {
-            auto find = _map.find(key);
+            const auto& find = _map.find(key);
             if (find == _map.end()) {
                 return false;
             }
diff --git a/src/Collections/List.hpp b/src/Collections/List.hpp
index 37c5579..52ad813 100644
--- a/src/Collections/List.hpp
+++ b/src/Collections/List.hpp
@@ -33,7 +33,7 @@ namespace Arbutils::Collections {
             return _vector.at(index);
         }
 
-        inline const_reference At(size_t index) const {
+        inline const const_reference& At(size_t index) const {
 #ifndef NO_ASSERT
             if (index >= _vector.size() || index < 0) {
                 std::stringstream ss;
@@ -44,7 +44,7 @@ namespace Arbutils::Collections {
             return _vector.at(index);
         }
 
-        inline const_reference Set(size_t index, const ValueT& value) {
+        inline const const_reference& Set(size_t index, const ValueT& value) {
 #ifndef NO_ASSERT
             if (index >= _vector.size() || index < 0) {
                 std::stringstream ss;
@@ -52,7 +52,7 @@ namespace Arbutils::Collections {
                 throw std::logic_error(ss.str());
             }
 #endif
-            auto prev = _vector.at(index);
+            const auto& prev = _vector.at(index);
             _vector[index] = value;
             return prev;
         }
@@ -65,7 +65,7 @@ namespace Arbutils::Collections {
         /// \param value The value we want the index for.
         /// \return The index of the first occurrence of the value in the list, or -1 if none is found.
         inline size_t IndexOf(const ValueT& value) const {
-            auto it = std::find(_vector.begin(), _vector.end(), value);
+            const auto& it = std::find(_vector.begin(), _vector.end(), value);
             if (it == _vector.end())
                 return -1;
             return std::distance(_vector.begin(), it);
@@ -76,7 +76,7 @@ namespace Arbutils::Collections {
         inline void Insert(size_t index, const ValueT& value) { _vector.insert(index, value); }
 
         inline reference operator[](size_t index) { return At(index); }
-        inline const_reference operator[](size_t index) const { return At(index); }
+        inline const const_reference& operator[](size_t index) const { return At(index); }
 
         inline size_t Count() const { return _vector.size(); }
         inline void Resize(size_t size) { _vector.resize(size); }