diff --git a/CMakeLists.txt b/CMakeLists.txt
index 4ab5bfd..cdc7816 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1,5 +1,5 @@
 cmake_minimum_required(VERSION 3.16)
-project(lockpp LANGUAGES CXX VERSION 2.4)
+project(lockpp LANGUAGES CXX VERSION 2.5)
 
 # --------------------------------------------------------------------------------------------------------
 # Library options
diff --git a/include/lockpp/lock.hpp b/include/lockpp/lock.hpp
index 1dc3de0..1cda68b 100644
--- a/include/lockpp/lock.hpp
+++ b/include/lockpp/lock.hpp
@@ -28,11 +28,11 @@ namespace lockpp
 
       public:
         template <template <typename> class Lock = write_lock, typename... LockArgs>
-        [[nodiscard]] locked<Type, Lock<Mutex>> write(LockArgs &&...);
+        [[nodiscard]] locked<Type, Lock<Mutex>> write(LockArgs &&...) &;
 
       public:
         template <template <typename> class Lock = read_lock, typename... LockArgs>
-        [[nodiscard]] locked<const Type, Lock<Mutex>> read(LockArgs &&...) const;
+        [[nodiscard]] locked<const Type, Lock<Mutex>> read(LockArgs &&...) const &;
 
       public:
         template <typename O>
diff --git a/include/lockpp/lock.inl b/include/lockpp/lock.inl
index 293318d..631ffd8 100644
--- a/include/lockpp/lock.inl
+++ b/include/lockpp/lock.inl
@@ -11,14 +11,14 @@ namespace lockpp
 
     template <typename Type, decayed Mutex>
     template <template <typename> class Lock, typename... LockArgs>
-    locked<Type, Lock<Mutex>> lock<Type, Mutex>::write(LockArgs &&...lock_args)
+    locked<Type, Lock<Mutex>> lock<Type, Mutex>::write(LockArgs &&...lock_args) &
     {
         return {&m_value, m_mutex, std::forward<LockArgs>(lock_args)...};
     }
 
     template <typename Type, decayed Mutex>
     template <template <typename> class Lock, typename... LockArgs>
-    locked<const Type, Lock<Mutex>> lock<Type, Mutex>::read(LockArgs &&...lock_args) const
+    locked<const Type, Lock<Mutex>> lock<Type, Mutex>::read(LockArgs &&...lock_args) const &
     {
         return {&m_value, m_mutex, std::forward<LockArgs>(lock_args)...};
     }
diff --git a/include/lockpp/locked.hpp b/include/lockpp/locked.hpp
index ac2d0b3..df6d720 100644
--- a/include/lockpp/locked.hpp
+++ b/include/lockpp/locked.hpp
@@ -18,8 +18,8 @@ namespace lockpp
         locked(Type *, lock_mutex_t<Lock> &, LockArgs &&...);
 
       public:
-        [[nodiscard]] Type &operator*() const noexcept;
-        [[nodiscard]] Type *operator->() const noexcept;
+        [[nodiscard]] Type &operator*() const & noexcept;
+        [[nodiscard]] Type *operator->() const & noexcept;
     };
 } // namespace lockpp
 
diff --git a/include/lockpp/locked.inl b/include/lockpp/locked.inl
index 9926604..94c8f74 100644
--- a/include/lockpp/locked.inl
+++ b/include/lockpp/locked.inl
@@ -13,13 +13,13 @@ namespace lockpp
     }
 
     template <typename Type, class Lock>
-    [[nodiscard]] Type &locked<Type, Lock>::operator*() const noexcept
+    [[nodiscard]] Type &locked<Type, Lock>::operator*() const & noexcept
     {
         return *m_value;
     }
 
     template <typename Type, class Lock>
-    [[nodiscard]] Type *locked<Type, Lock>::operator->() const noexcept
+    [[nodiscard]] Type *locked<Type, Lock>::operator->() const & noexcept
     {
         return m_value;
     }