diff --git a/include/turtle/detail/action.hpp b/include/turtle/detail/action.hpp
index 7bc5fa0..8b267e5 100644
--- a/include/turtle/detail/action.hpp
+++ b/include/turtle/detail/action.hpp
@@ -62,6 +62,27 @@ namespace mock { namespace detail {
         action_type a_;
     };
 
+    /// Type erased value storage
+    struct value
+    {
+        value() = default;
+        value(const value&) = delete;
+        value& operator=(const value&) = delete;
+        virtual ~value() = default;
+    };
+    /// Actual value storage,
+    /// holds an instance of T (stripped of reference qualifiers)
+    template<typename T>
+    struct value_imp : value
+    {
+        using type = std::remove_const_t<std::remove_reference_t<T>>;
+
+        template<typename U>
+        value_imp(U&& t) : t_(std::forward<U>(t))
+        {}
+        type t_;
+    };
+
     template<typename Result, typename Signature>
     class action : public action_base<Result, Signature>
     {
@@ -85,24 +106,6 @@ namespace mock { namespace detail {
         }
 
     private:
-        struct value
-        {
-            value() = default;
-            value(const value&) = delete;
-            value& operator=(const value&) = delete;
-            virtual ~value() = default;
-        };
-        template<typename T>
-        struct value_imp : value
-        {
-            typedef std::remove_const_t<std::remove_reference_t<T>> type;
-
-            template<typename U>
-            value_imp(U&& t) : t_(std::forward<U>(t))
-            {}
-            type t_;
-        };
-
         template<typename T>
         typename value_imp<T>::type& store(T&& t)
         {
diff --git a/include/turtle/detail/expectation.hpp b/include/turtle/detail/expectation.hpp
index 5c23895..cd107dc 100644
--- a/include/turtle/detail/expectation.hpp
+++ b/include/turtle/detail/expectation.hpp
@@ -27,7 +27,8 @@ namespace mock { namespace detail {
         bool operator()(typename ref_arg<Args>::type...) override { return true; }
         void serialize(std::ostream& s) const override
         {
-            for(unsigned i = 0; i < sizeof...(Args); ++i)
+            constexpr auto arity = sizeof...(Args);
+            for(unsigned i = 0; i < arity; ++i)
             {
                 if(i)
                     s << ", ";
@@ -99,7 +100,7 @@ namespace mock { namespace detail {
     template<typename R, typename... Args>
     class expectation<R(Args...)> : public action<R, R(Args...)>
     {
-        static constexpr auto arity = sizeof...(Args);
+        static constexpr std::size_t arity = sizeof...(Args);
 
     public:
         expectation() : expectation("unknown location", 0) {}
@@ -122,13 +123,13 @@ namespace mock { namespace detail {
         void invoke(std::unique_ptr<invocation> i) { invocation_ = std::move(i); }
 
         template<typename... Constraints>
-        std::enable_if_t<(arity > 0) && sizeof...(Constraints) == arity, expectation&> with(Constraints... c)
+        std::enable_if_t<(arity > 0u) && sizeof...(Constraints) == arity, expectation&> with(Constraints... c)
         {
             matcher_ = std::make_unique<single_matcher<void(Constraints...), Args...>>(c...);
             return *this;
         }
         template<typename Constraint, std::size_t Arity = arity>
-        std::enable_if_t<(Arity > 1), expectation&> with(const Constraint& c)
+        std::enable_if_t<(Arity > 1u), expectation&> with(const Constraint& c)
         {
             matcher_ = std::make_unique<multi_matcher<Constraint, Args...>>(c);
             return *this;
diff --git a/include/turtle/detail/function_impl.hpp b/include/turtle/detail/function_impl.hpp
index 8cbbd1f..1c0bea4 100644
--- a/include/turtle/detail/function_impl.hpp
+++ b/include/turtle/detail/function_impl.hpp
@@ -69,6 +69,9 @@ namespace mock { namespace detail {
 #endif
     }
 
+    template<typename... Arg>
+    class lazy_args;
+
     template<typename Signature>
     class function_impl;
 
@@ -133,7 +136,7 @@ namespace mock { namespace detail {
         {
         private:
             typedef wrapper_base<R, expectation_type> base_type;
-            static constexpr auto arity = sizeof...(Args);
+            static constexpr std::size_t arity = sizeof...(Args);
 
         public:
             wrapper(const std::shared_ptr<mutex>& m, expectation_type& e) : base_type(e), lock_(m) {}
@@ -238,8 +241,9 @@ namespace mock { namespace detail {
         R operator()(Args... args) const
         {
 // Due to lifetime rules of references this must be created and consumed in one line
-#define MOCK_FUNCTION_CONTEXT \
-    boost::unit_test::lazy_ostream::instance() << lazy_context(this) << lazy_args(args...) << lazy_expectations(this)
+#define MOCK_FUNCTION_CONTEXT                  \
+    boost::unit_test::lazy_ostream::instance() \
+      << lazy_context(this) << lazy_args<Args...>(args...) << lazy_expectations(this)
 
             lock _(mutex_);
             valid_ = false;
@@ -316,35 +320,49 @@ namespace mock { namespace detail {
             const function_impl* impl_;
         };
 
-        struct lazy_args
-        {
-            lazy_args(std::add_lvalue_reference_t<Args>... args) : args_(args...) {}
-            friend std::ostream& operator<<(std::ostream& s, const lazy_args& a)
-            {
-                return a.print_impl(std::make_index_sequence<sizeof...(Args)>{}, s);
-            }
-
-        private:
-            std::tuple<std::add_lvalue_reference_t<Args>...> args_;
-
-            template<std::size_t... I>
-            std::ostream& print_impl(std::index_sequence<I...>, std::ostream& s) const
-            {
-                s << '(';
-                using expander = int[];
-                (void)expander{
-                    0, (s << ' ' << mock::format(std::get<I>(args_)) << (sizeof...(Args) - 1u == I ? ' ' : ','), 0)...
-                };
-                return s << ')';
-            }
-        };
-
         std::list<expectation_type> expectations_;
         context* context_;
         mutable bool valid_;
         const int exceptions_;
         const std::shared_ptr<mutex> mutex_;
     };
+
+    template<typename ArgFirst, typename... ArgRest>
+    class lazy_args<ArgFirst, ArgRest...> : lazy_args<ArgRest...>
+    {
+        ArgFirst& arg_;
+
+    public:
+        lazy_args(ArgFirst& arg, std::add_lvalue_reference_t<ArgRest>... args)
+            : lazy_args<ArgRest...>(args...), arg_(arg)
+        {}
+        std::ostream& print(std::ostream& s) const
+        {
+            s << ' ' << mock::format(arg_) << ',';
+            return lazy_args<ArgRest...>::print(s);
+        }
+    };
+    template<typename ArgFirst>
+    class lazy_args<ArgFirst>
+    {
+        ArgFirst& arg_;
+
+    public:
+        lazy_args(ArgFirst& arg) : arg_(arg) {}
+        std::ostream& print(std::ostream& s) const { return s << ' ' << mock::format(arg_) << ' '; }
+    };
+    template<>
+    class lazy_args<>
+    {
+    public:
+        std::ostream& print(std::ostream& s) const { return s; }
+    };
+    template<typename... Args>
+    std::ostream& operator<<(std::ostream& s, const lazy_args<Args...>& a)
+    {
+        s << '(';
+        return a.print(s) << ')';
+    }
 }} // namespace mock::detail
 
 #endif // MOCK_FUNCTION_IMPL_HPP_INCLUDED