diff --git a/include/sp/common/ByteSwapping.h b/include/sp/common/ByteSwapping.h
index 5eb2e5a..f8754c7 100644
--- a/include/sp/common/ByteSwapping.h
+++ b/include/sp/common/ByteSwapping.h
@@ -16,7 +16,7 @@ void SwapBytes(T& value) {
 	std::reverse(ptr, ptr + sizeof(T));
 }
 
-bool IsSystemBigEndian() {
+static bool IsSystemBigEndian() {
 	static constexpr std::uint16_t test = 10;
 	static const bool isBigEndian = reinterpret_cast<const std::uint8_t*>(&test)[1] == 10;
 	return isBigEndian;
diff --git a/include/sp/protocol/message/MessageInterfacesImpl.h b/include/sp/protocol/message/MessageInterfacesImpl.h
index 9ccf3f9..5f464a8 100644
--- a/include/sp/protocol/message/MessageInterfacesImpl.h
+++ b/include/sp/protocol/message/MessageInterfacesImpl.h
@@ -30,7 +30,7 @@ class MessageInterfaceBigEndian : public TBase {
 	}
 
 	template <typename T>
-	void WriteData(T value, DataBuffer& buffer) {
+	void WriteData(T value, DataBuffer& buffer) const {
 		ToNetwork(value);
 		buffer << value;
 	}
@@ -71,12 +71,12 @@ class MessageInterfaceReadBase : public TBase {
 template <typename TBase>
 class MessageInterfaceWriteBase : public TBase {
   public:
-	void Write(DataBuffer& buffer) {
+	void Write(DataBuffer& buffer) const {
 		WriteImpl(buffer);
 	}
 
   protected:
-	virtual void WriteImpl(DataBuffer& buffer) = 0;
+	virtual void WriteImpl(DataBuffer& buffer) const = 0;
 };
 
 // Handler functionality chunk
@@ -85,12 +85,12 @@ class MessageInterfaceHandlerBase : public TBase {
   public:
 	using HandlerType = typename THandler::HandlerT;
 
-	void Dispatch(HandlerType& handler) {
+	void Dispatch(HandlerType& handler) const {
 		DispatchImpl(handler);
 	}
 
   protected:
-	virtual void DispatchImpl(HandlerType& handler) = 0;
+	virtual void DispatchImpl(HandlerType& handler) const = 0;
 };
 
 // Validity functionality chunk
@@ -109,7 +109,7 @@ class MessageInterfaceValidityBase : public TBase {
 template <typename TBase>
 class MessageInterfaceWriteIdBase : public TBase {
   public:
-	void Write(DataBuffer& buffer) {
+	void Write(DataBuffer& buffer) const {
 		this->WriteData(this->GetId(), buffer);
 		this->WriteImpl(buffer);
 	}
diff --git a/include/sp/protocol/message/MessagesImpl.h b/include/sp/protocol/message/MessagesImpl.h
index 00a5b45..fd4838a 100644
--- a/include/sp/protocol/message/MessagesImpl.h
+++ b/include/sp/protocol/message/MessagesImpl.h
@@ -26,8 +26,8 @@ class MessageImplDispatchBase : public TBase {
 	using Handler = typename TBase::HandlerType;
 
   protected:
-	virtual void DispatchImpl(Handler& handler) override {
-		handler.Handle(static_cast<TActual&>(*this));
+	virtual void DispatchImpl(Handler& handler) const override {
+		handler.Handle(static_cast<const TActual&>(*this));
 	}
 };
 
@@ -113,13 +113,13 @@ class MessageImplFieldsWriteBase : public TBase {
   private:
 	// normal writing
 	template <typename TField>
-	void WriteField(Field<TField, 0>& field, DataBuffer& buffer) {
+	void WriteField(const Field<TField, 0>& field, DataBuffer& buffer) const {
 		this->WriteData(field.GetValue(), buffer);
 	}
 
 	// writing field in bitfield
 	template <typename TFieldType, typename TField, int IAlignment>
-	void WriteField(Field<TField, IAlignment>& field, TFieldType& data, std::size_t offset) {
+	void WriteField(const Field<TField, IAlignment>& field, TFieldType& data, std::size_t offset) const {
 		static constexpr std::size_t TotalBitCount = sizeof(TFieldType) * 8;
 		// we suppose that the first element is at the highest bits
 		data |= (field.GetValue() & ((1 << IAlignment) - 1)) << TotalBitCount - IAlignment - offset;
@@ -127,7 +127,7 @@ class MessageImplFieldsWriteBase : public TBase {
 
 	// writing bitfield
 	template <typename TContainer, typename TFirst, typename... TFields>
-	void WriteField(Field<BitField<TContainer, TFirst, TFields...>, 0>& field, DataBuffer& buffer) {
+	void WriteField(const Field<BitField<TContainer, TFirst, TFields...>, 0>& field, DataBuffer& buffer) const {
 		TContainer data = 0;
 		std::size_t offset = 0;
 		TupleForEach(
@@ -139,9 +139,9 @@ class MessageImplFieldsWriteBase : public TBase {
 		this->WriteData(data, buffer);
 	}
 
-	void WriteImpl(DataBuffer& buffer) override {
+	void WriteImpl(DataBuffer& buffer) const override {
 		auto& allFields = this->GetFields();
-		TupleForEach([&buffer, this](auto& field) { this->WriteField(field, buffer); }, allFields);
+		TupleForEach([&buffer, this](const auto& field) { this->WriteField(field, buffer); }, allFields);
 	}
 };