diff --git a/include/serial.h b/include/serial.h
index 8e25b04..d574089 100644
--- a/include/serial.h
+++ b/include/serial.h
@@ -47,6 +47,12 @@
 #include <boost/bind.hpp>
 #include <boost/thread.hpp>
 
+// A macro to disallow the copy constructor and operator= functions
+// This should be used in the private: declarations for a class
+#define DISALLOW_COPY_AND_ASSIGN(TypeName) \
+  TypeName(const TypeName&);               \
+  void operator=(const TypeName&)
+
 // DEFINES
 #define DEFAULT_BAUDRATE 9600
 #define DEFAULT_TIMEOUT 0.0
@@ -132,7 +138,7 @@ public:
     * 
     * @return An integer representing the number of bytes read.
     */
-    int read(char* buffer, int size = 1);
+    const int read(char* buffer, int size = 1);
     
     /** Read size bytes from the serial port.
     * If a timeout is set it may return less characters than requested. With no timeout
@@ -142,7 +148,7 @@ public:
     * 
     * @return A std::string containing the data read.
     */
-    std::string read(int size = 1);
+    const std::string read(int size = 1);
     
     /** Write length bytes from buffer to the serial port.
     * 
@@ -152,7 +158,7 @@ public:
     * 
     * @return An integer representing the number of bytes written.
     */
-    int write(char data[], int length);
+    const int write(char data[], int length);
     
     /** Write a string to the serial port.
     * 
@@ -160,7 +166,7 @@ public:
     * 
     * @return An integer representing the number of bytes written to the serial port.
     */
-    int write(std::string data);
+    const int write(std::string data);
     
     /** Sets the logic level of the RTS line.
     * 
@@ -178,13 +184,13 @@ public:
     * 
     * @return A boolean value that represents the current logic level of the CTS line.
     */
-    bool getCTS();
+    const bool getCTS();
     
     /** Gets the status of the DSR line.
     * 
     * @return A boolean value that represents the current logic level of the DSR line.
     */
-    bool getDSR();
+    const bool getDSR();
     
     /** Sets the timeout for reads in seconds.
     * 
@@ -206,7 +212,7 @@ public:
     *        zero (-1) will result in infinite blocking behaviour, i.e. the serial port will
     *        block until either size bytes have been read or an exception has occured.
     */
-    long getTimeoutMilliseconds();
+    const long getTimeoutMilliseconds();
     
     /** Sets the baudrate for the serial port.
     * 
@@ -218,7 +224,7 @@ public:
     * 
     * @return An integer that sets the baud rate for the serial port.
     */
-    int getBaudrate();
+    const int getBaudrate();
     
     /** Sets the bytesize for the serial port.
     * 
@@ -238,7 +244,7 @@ public:
     * 
     * @throw InvalidBytesizeException
     */
-    bytesize_t getBytesize();
+    const bytesize_t getBytesize();
     
     /** Sets the parity for the serial port.
     * 
@@ -256,7 +262,7 @@ public:
     * 
     * @throw InvalidParityException
     */
-    parity_t getParity();
+    const parity_t getParity();
     
     /** Sets the stopbits for the serial port.
     * 
@@ -274,7 +280,7 @@ public:
     * 
     * @throw InvalidStopbitsException
     */
-    stopbits_t getStopbits();
+    const stopbits_t getStopbits();
     
     /** Sets the flow control for the serial port.
     * 
@@ -292,8 +298,9 @@ public:
     * 
     * @throw InvalidFlowcontrolException
     */
-    flowcontrol_t getFlowcontrol();
+    const flowcontrol_t getFlowcontrol();
 private:
+    DISALLOW_COPY_AND_ASSIGN(Serial);
     void init();
     void read_complete(const boost::system::error_code& error, std::size_t bytes_transferred);
     void timeout_callback(const boost::system::error_code& error);
diff --git a/src/serial.cpp b/src/serial.cpp
index e2b0732..72b89a9 100644
--- a/src/serial.cpp
+++ b/src/serial.cpp
@@ -189,7 +189,7 @@ void Serial::close() {
     this->serial_port->close();
 }
 
-int Serial::read(char* buffer, int size) {
+const int Serial::read(char* buffer, int size) {
     this->reading = true;
     if(this->nonblocking) // Do not wait for data
         boost::asio::async_read(*this->serial_port, boost::asio::buffer(buffer, size),
@@ -215,7 +215,7 @@ int Serial::read(char* buffer, int size) {
     return this->bytes_read;
 }
 
-std::string Serial::read(int size) {
+const std::string Serial::read(int size) {
     char *serial_buffer = new char[size];
     int bytes_read_ = this->read(serial_buffer, size);
     std::string return_str(serial_buffer, (std::size_t)bytes_read_);
@@ -240,11 +240,11 @@ void Serial::timeout_callback(const boost::system::error_code& error) {
     }
 }
 
-int Serial::write(char data[], int length) {
+const int Serial::write(char data[], int length) {
     return boost::asio::write(*this->serial_port, boost::asio::buffer(data, length), boost::asio::transfer_all());
 }
 
-int Serial::write(std::string data) {
+const int Serial::write(std::string data) {
     char *cstr = new char[data.size()+1];
     std::strcpy(cstr, data.c_str());
     int bytes_wrote = this->write(cstr, data.length());
@@ -260,12 +260,12 @@ void Serial::setDTR(bool level) {
     this->serial_port->set_option(DTRControl(level));
 }
 
-bool Serial::getCTS() {
+const bool Serial::getCTS() {
     throw(boost::asio::error::operation_not_supported);
     return false;
 }
 
-bool Serial::getDSR() {
+const bool Serial::getDSR() {
     throw(boost::asio::error::operation_not_supported);
     return false;
 }
@@ -286,7 +286,7 @@ void Serial::setTimeoutMilliseconds(long timeout) {
         this->nonblocking = false;
 }
 
-long Serial::getTimeoutMilliseconds() {
+const long Serial::getTimeoutMilliseconds() {
     return this->timeout->total_milliseconds();
 }
 
@@ -294,7 +294,7 @@ void Serial::setBaudrate(int baudrate) {
     this->baudrate = boost::asio::serial_port_base::baud_rate(baudrate);
 }
 
-int Serial::getBaudrate() {
+const int Serial::getBaudrate() {
     return this->baudrate.value();
 }
 
@@ -318,7 +318,7 @@ void Serial::setBytesize(bytesize_t bytesize) {
     }
 }
 
-bytesize_t Serial::getBytesize() {
+const bytesize_t Serial::getBytesize() {
     return bytesize_t(this->bytesize.value());
 }
 
@@ -339,7 +339,7 @@ void Serial::setParity(parity_t parity) {
     }
 }
 
-parity_t Serial::getParity() {
+const parity_t Serial::getParity() {
     switch(this->parity.value()) {
         case boost::asio::serial_port_base::parity::none:
             return parity_t(PARITY_NONE);
@@ -369,7 +369,7 @@ void Serial::setStopbits(stopbits_t stopbits) {
     }
 }
 
-stopbits_t Serial::getStopbits() {
+const stopbits_t Serial::getStopbits() {
     switch(this->stopbits.value()) {
         case boost::asio::serial_port_base::stop_bits::one:
             return stopbits_t(STOPBITS_ONE);
@@ -399,7 +399,7 @@ void Serial::setFlowcontrol(flowcontrol_t flowcontrol) {
     }
 }
 
-flowcontrol_t Serial::getFlowcontrol() {
+const flowcontrol_t Serial::getFlowcontrol() {
     switch(this->flowcontrol.value()) {
         case boost::asio::serial_port_base::flow_control::none:
             return flowcontrol_t(FLOWCONTROL_NONE);