diff --git a/dev/test/so_5/message_limits/CMakeLists.txt b/dev/test/so_5/message_limits/CMakeLists.txt
index 3d378e41..cec5beb2 100644
--- a/dev/test/so_5/message_limits/CMakeLists.txt
+++ b/dev/test/so_5/message_limits/CMakeLists.txt
@@ -8,6 +8,8 @@ add_subdirectory(redirect_msg_too_deep)
 add_subdirectory(subscr_without_limit)
 add_subdirectory(transform_msg)
 add_subdirectory(transform_msg_too_deep)
+add_subdirectory(transform_to_mutable_msg)
+add_subdirectory(transform_to_mutable_msg_2)
 add_subdirectory(another_direct_mbox)
 add_subdirectory(redirect_from_timer_to_full_mchain)
 add_subdirectory(transform_from_timer_to_full_mchain)
diff --git a/dev/test/so_5/message_limits/build_tests.rb b/dev/test/so_5/message_limits/build_tests.rb
index 196df235..c85ec956 100644
--- a/dev/test/so_5/message_limits/build_tests.rb
+++ b/dev/test/so_5/message_limits/build_tests.rb
@@ -28,6 +28,8 @@
 	required_prj "#{path}/transform_msg/sc_mbox/prj.ut.rb"
 	required_prj "#{path}/transform_msg_too_deep/mc_mbox/prj.ut.rb"
 	required_prj "#{path}/transform_msg_too_deep/sc_mbox/prj.ut.rb"
+	required_prj "#{path}/transform_to_mutable_msg/prj.ut.rb"
+	required_prj "#{path}/transform_to_mutable_msg_2/prj.ut.rb"
 
 	required_prj "#{path}/another_direct_mbox/prj.ut.rb"
 
diff --git a/dev/test/so_5/message_limits/transform_to_mutable_msg/CMakeLists.txt b/dev/test/so_5/message_limits/transform_to_mutable_msg/CMakeLists.txt
new file mode 100644
index 00000000..e826da4d
--- /dev/null
+++ b/dev/test/so_5/message_limits/transform_to_mutable_msg/CMakeLists.txt
@@ -0,0 +1,2 @@
+set(UNITTEST _unit.test.message_limits.transform_to_mutable_msg)
+include(${CMAKE_SOURCE_DIR}/cmake/unittest.cmake)
diff --git a/dev/test/so_5/message_limits/transform_to_mutable_msg/main.cpp b/dev/test/so_5/message_limits/transform_to_mutable_msg/main.cpp
new file mode 100644
index 00000000..ea1ab687
--- /dev/null
+++ b/dev/test/so_5/message_limits/transform_to_mutable_msg/main.cpp
@@ -0,0 +1,115 @@
+/*
+ * A test for trasformation of an immutable message into a mutable message.
+ */
+
+#include <iostream>
+#include <map>
+#include <exception>
+#include <stdexcept>
+#include <cstdlib>
+#include <thread>
+#include <chrono>
+
+#include <so_5/all.hpp>
+
+#include <test/3rd_party/various_helpers/time_limited_execution.hpp>
+
+struct msg_initial_message final : public so_5::message_t
+{
+	const std::string m_msg;
+
+	msg_initial_message( std::string msg ) : m_msg{ std::move(msg) }
+	{}
+};
+
+struct msg_transformed_message final : public so_5::message_t
+{
+	std::string m_msg;
+
+	msg_transformed_message( std::string msg ) : m_msg{ std::move(msg) }
+	{}
+};
+
+class agent_with_limit_t final : public so_5::agent_t
+{
+public :
+	agent_with_limit_t(
+		context_t ctx )
+		:	so_5::agent_t{ ctx
+				+ limit_then_transform( 1u,
+						[this]( const msg_initial_message & msg ) {
+							return make_transformed<
+										so_5::mutable_msg< msg_transformed_message > >(
+									so_direct_mbox(),
+									"<" + msg.m_msg + ">" );
+						} )
+				+ limit_then_abort< so_5::mutable_msg< msg_transformed_message > >( 1u )
+			}
+	{}
+
+	void
+	so_define_agent() override
+	{
+		so_subscribe_self()
+			.event( [this]( mhood_t<msg_initial_message> cmd ) {
+					m_received += "[initial:" + cmd->m_msg + "]";
+				} )
+			.event( [this]( mutable_mhood_t<msg_transformed_message> cmd ) {
+					m_received += "[transformed:" + cmd->m_msg + "]";
+
+					const std::string expected =
+						"[initial:hello][transformed:<bye>]";
+
+					if( expected != m_received )
+						throw std::runtime_error( expected + " != " + m_received );
+					else
+						so_deregister_agent_coop_normally();
+				} )
+			;
+	}
+
+	virtual void
+	so_evt_start() override
+	{
+		so_5::send< msg_initial_message >( *this, "hello" );
+		so_5::send< msg_initial_message >( *this, "bye" );
+	}
+
+private :
+	std::string m_received;
+};
+
+void
+init( so_5::environment_t & env )
+{
+	env.introduce_coop(
+			[]( so_5::coop_t & coop ) {
+				coop.make_agent< agent_with_limit_t >();
+			} );
+}
+
+int
+main()
+{
+	try
+	{
+		run_with_time_limit(
+			[]()
+			{
+				so_5::launch( &init,
+					[](so_5::environment_params_t & params) {
+						params.message_delivery_tracer(
+								so_5::msg_tracing::std_cout_tracer() );
+					} );
+			},
+			5 );
+	}
+	catch( const std::exception & ex )
+	{
+		std::cerr << "Error: " << ex.what() << std::endl;
+		return 1;
+	}
+
+	return 0;
+}
+
diff --git a/dev/test/so_5/message_limits/transform_to_mutable_msg/prj.rb b/dev/test/so_5/message_limits/transform_to_mutable_msg/prj.rb
new file mode 100644
index 00000000..72a61dee
--- /dev/null
+++ b/dev/test/so_5/message_limits/transform_to_mutable_msg/prj.rb
@@ -0,0 +1,11 @@
+require 'mxx_ru/cpp'
+
+MxxRu::Cpp::exe_target {
+
+	required_prj 'so_5/prj.rb'
+
+	target '_unit.test.message_limits.transform_to_mutable_msg'
+
+	cpp_source 'main.cpp'
+}
+
diff --git a/dev/test/so_5/message_limits/transform_to_mutable_msg/prj.ut.rb b/dev/test/so_5/message_limits/transform_to_mutable_msg/prj.ut.rb
new file mode 100644
index 00000000..b271b4ed
--- /dev/null
+++ b/dev/test/so_5/message_limits/transform_to_mutable_msg/prj.ut.rb
@@ -0,0 +1,9 @@
+require 'mxx_ru/binary_unittest'
+
+path = 'test/so_5/message_limits/transform_to_mutable_msg'
+
+MxxRu::setup_target(
+	MxxRu::BinaryUnittestTarget.new(
+		"#{path}/prj.ut.rb",
+		"#{path}/prj.rb" )
+)
diff --git a/dev/test/so_5/message_limits/transform_to_mutable_msg_2/CMakeLists.txt b/dev/test/so_5/message_limits/transform_to_mutable_msg_2/CMakeLists.txt
new file mode 100644
index 00000000..b423ae02
--- /dev/null
+++ b/dev/test/so_5/message_limits/transform_to_mutable_msg_2/CMakeLists.txt
@@ -0,0 +1,2 @@
+set(UNITTEST _unit.test.message_limits.transform_to_mutable_msg_2)
+include(${CMAKE_SOURCE_DIR}/cmake/unittest.cmake)
diff --git a/dev/test/so_5/message_limits/transform_to_mutable_msg_2/main.cpp b/dev/test/so_5/message_limits/transform_to_mutable_msg_2/main.cpp
new file mode 100644
index 00000000..39b85886
--- /dev/null
+++ b/dev/test/so_5/message_limits/transform_to_mutable_msg_2/main.cpp
@@ -0,0 +1,116 @@
+/*
+ * A test for trasformation of an immutable message into a mutable message.
+ * Messages that not derived from so_5::message_t are used.
+ */
+
+#include <iostream>
+#include <map>
+#include <exception>
+#include <stdexcept>
+#include <cstdlib>
+#include <thread>
+#include <chrono>
+
+#include <so_5/all.hpp>
+
+#include <test/3rd_party/various_helpers/time_limited_execution.hpp>
+
+struct msg_initial_message
+{
+	const std::string m_msg;
+
+	msg_initial_message( std::string msg ) : m_msg{ std::move(msg) }
+	{}
+};
+
+struct msg_transformed_message
+{
+	std::string m_msg;
+
+	msg_transformed_message( std::string msg ) : m_msg{ std::move(msg) }
+	{}
+};
+
+class agent_with_limit_t final : public so_5::agent_t
+{
+public :
+	agent_with_limit_t(
+		context_t ctx )
+		:	so_5::agent_t{ ctx
+				+ limit_then_transform( 1u,
+						[this]( const msg_initial_message & msg ) {
+							return make_transformed<
+										so_5::mutable_msg< msg_transformed_message > >(
+									so_direct_mbox(),
+									"<" + msg.m_msg + ">" );
+						} )
+				+ limit_then_abort< so_5::mutable_msg< msg_transformed_message > >( 1u )
+			}
+	{}
+
+	void
+	so_define_agent() override
+	{
+		so_subscribe_self()
+			.event( [this]( mhood_t<msg_initial_message> cmd ) {
+					m_received += "[initial:" + cmd->m_msg + "]";
+				} )
+			.event( [this]( mutable_mhood_t<msg_transformed_message> cmd ) {
+					m_received += "[transformed:" + cmd->m_msg + "]";
+
+					const std::string expected =
+						"[initial:hello][transformed:<bye>]";
+
+					if( expected != m_received )
+						throw std::runtime_error( expected + " != " + m_received );
+					else
+						so_deregister_agent_coop_normally();
+				} )
+			;
+	}
+
+	virtual void
+	so_evt_start() override
+	{
+		so_5::send< msg_initial_message >( *this, "hello" );
+		so_5::send< msg_initial_message >( *this, "bye" );
+	}
+
+private :
+	std::string m_received;
+};
+
+void
+init( so_5::environment_t & env )
+{
+	env.introduce_coop(
+			[]( so_5::coop_t & coop ) {
+				coop.make_agent< agent_with_limit_t >();
+			} );
+}
+
+int
+main()
+{
+	try
+	{
+		run_with_time_limit(
+			[]()
+			{
+				so_5::launch( &init,
+					[](so_5::environment_params_t & params) {
+						params.message_delivery_tracer(
+								so_5::msg_tracing::std_cout_tracer() );
+					} );
+			},
+			5 );
+	}
+	catch( const std::exception & ex )
+	{
+		std::cerr << "Error: " << ex.what() << std::endl;
+		return 1;
+	}
+
+	return 0;
+}
+
diff --git a/dev/test/so_5/message_limits/transform_to_mutable_msg_2/prj.rb b/dev/test/so_5/message_limits/transform_to_mutable_msg_2/prj.rb
new file mode 100644
index 00000000..80c6703c
--- /dev/null
+++ b/dev/test/so_5/message_limits/transform_to_mutable_msg_2/prj.rb
@@ -0,0 +1,11 @@
+require 'mxx_ru/cpp'
+
+MxxRu::Cpp::exe_target {
+
+	required_prj 'so_5/prj.rb'
+
+	target '_unit.test.message_limits.transform_to_mutable_msg_2'
+
+	cpp_source 'main.cpp'
+}
+
diff --git a/dev/test/so_5/message_limits/transform_to_mutable_msg_2/prj.ut.rb b/dev/test/so_5/message_limits/transform_to_mutable_msg_2/prj.ut.rb
new file mode 100644
index 00000000..691e78c5
--- /dev/null
+++ b/dev/test/so_5/message_limits/transform_to_mutable_msg_2/prj.ut.rb
@@ -0,0 +1,9 @@
+require 'mxx_ru/binary_unittest'
+
+path = 'test/so_5/message_limits/transform_to_mutable_msg_2'
+
+MxxRu::setup_target(
+	MxxRu::BinaryUnittestTarget.new(
+		"#{path}/prj.ut.rb",
+		"#{path}/prj.rb" )
+)