diff --git a/src/Arduino_ESP32_OTA.cpp b/src/Arduino_ESP32_OTA.cpp
index 13a7d92..d500961 100644
--- a/src/Arduino_ESP32_OTA.cpp
+++ b/src/Arduino_ESP32_OTA.cpp
@@ -26,26 +26,6 @@
 #include "decompress/utility.h"
 #include "esp_ota_ops.h"
 
-/* Used to bind local module function to actual class instance */
-static Arduino_ESP32_OTA * _esp_ota_obj_ptr = 0;
-
-/******************************************************************************
-   LOCAL MODULE FUNCTIONS
- ******************************************************************************/
-
-static uint8_t read_byte() {
-  if(_esp_ota_obj_ptr) {
-    return _esp_ota_obj_ptr->read_byte_from_network();
-  }
-  return -1;
-}
-
-static void write_byte(uint8_t data) {
-  if(_esp_ota_obj_ptr) {
-    _esp_ota_obj_ptr->write_byte_to_flash(data);
-  }
-}
-
 /******************************************************************************
    CTOR/DTOR
  ******************************************************************************/
@@ -57,6 +37,7 @@ Arduino_ESP32_OTA::Arduino_ESP32_OTA()
 ,_crc32(0)
 ,_ca_cert{amazon_root_ca}
 ,_ca_cert_bundle{nullptr}
+,_magic(0)
 {
 
 }
@@ -65,22 +46,22 @@ Arduino_ESP32_OTA::Arduino_ESP32_OTA()
    PUBLIC MEMBER FUNCTIONS
  ******************************************************************************/
 
-Arduino_ESP32_OTA::Error Arduino_ESP32_OTA::begin()
+Arduino_ESP32_OTA::Error Arduino_ESP32_OTA::begin(uint32_t magic)
 {
-  _esp_ota_obj_ptr = this;
+  /* initialize private variables */
+  otaInit();
 
   /* ... initialize CRC ... */
-  _crc32 = 0xFFFFFFFF;
+  crc32Init();
+
+  /* ... configure board Magic number */
+  setMagic(magic);
 
   if(!isCapable()) {
     DEBUG_ERROR("%s: board is not capable to perform OTA", __FUNCTION__);
     return Error::NoOtaStorage;
   }
 
-  /* initialize private variables */
-  _ota_size = 0;
-  _ota_header = {0};
-
   if(Update.isRunning()) {
     Update.abort();
     DEBUG_DEBUG("%s: Aborting running update", __FUNCTION__);
@@ -107,6 +88,11 @@ void Arduino_ESP32_OTA::setCACertBundle (const uint8_t * bundle)
   }
 }
 
+void Arduino_ESP32_OTA::setMagic(uint32_t magic)
+{
+  _magic = magic;
+}
+
 uint8_t Arduino_ESP32_OTA::read_byte_from_network()
 {
   bool is_http_data_timeout = false;
@@ -119,7 +105,7 @@ uint8_t Arduino_ESP32_OTA::read_byte_from_network()
     }
     if (_client->available()) {
       const uint8_t data = _client->read();
-      _crc32 = crc_update(_crc32, &data, 1);
+      crc32Update(data);
       return data;
     }
   }
@@ -262,7 +248,7 @@ int Arduino_ESP32_OTA::download(const char * ota_url)
   }
 
   /* ... and OTA magic number */
-  if (_ota_header.header.magic_number != ARDUINO_ESP32_OTA_MAGIC)
+  if (_ota_header.header.magic_number != _magic)
   {
     delete _client;
     _client = nullptr;
@@ -273,7 +259,7 @@ int Arduino_ESP32_OTA::download(const char * ota_url)
   _crc32 = crc_update(_crc32, &_ota_header.header.magic_number, 12);
 
   /* Download and decode OTA file */
-  _ota_size = lzss_download(read_byte, write_byte, content_length_val - sizeof(_ota_header));
+  _ota_size = lzss_download(this, content_length_val - sizeof(_ota_header));
 
   if(_ota_size <= content_length_val - sizeof(_ota_header))
   {
@@ -289,10 +275,10 @@ int Arduino_ESP32_OTA::download(const char * ota_url)
 
 Arduino_ESP32_OTA::Error Arduino_ESP32_OTA::update()
 {
-  /* ... then finalise ... */
-  _crc32 ^= 0xFFFFFFFF;
+  /* ... then finalize ... */
+  crc32Finalize();
 
-  if(_crc32 != _ota_header.header.crc32) {
+  if(!crc32Verify()) {
     DEBUG_ERROR("%s: CRC32 mismatch", __FUNCTION__);
     return Error::OtaHeaderCrc;
   }
@@ -316,3 +302,33 @@ bool Arduino_ESP32_OTA::isCapable()
   const esp_partition_t * ota_1  = esp_partition_find_first(ESP_PARTITION_TYPE_APP, ESP_PARTITION_SUBTYPE_APP_OTA_1, NULL);
   return ((ota_0 != nullptr) && (ota_1 != nullptr));
 }
+
+/******************************************************************************
+   PROTECTED MEMBER FUNCTIONS
+ ******************************************************************************/
+
+void Arduino_ESP32_OTA::otaInit()
+{
+  _ota_size = 0;
+  _ota_header = {0};
+}
+
+void Arduino_ESP32_OTA::crc32Init()
+{
+  _crc32 = 0xFFFFFFFF;
+}
+
+void Arduino_ESP32_OTA::crc32Update(const uint8_t data)
+{
+  _crc32 = crc_update(_crc32, &data, 1);
+}
+
+void Arduino_ESP32_OTA::crc32Finalize()
+{
+  _crc32 ^= 0xFFFFFFFF;
+}
+
+bool Arduino_ESP32_OTA::crc32Verify()
+{
+  return (_crc32 == _ota_header.header.crc32);
+}
diff --git a/src/Arduino_ESP32_OTA.h b/src/Arduino_ESP32_OTA.h
index 069d22b..34046d8 100644
--- a/src/Arduino_ESP32_OTA.h
+++ b/src/Arduino_ESP32_OTA.h
@@ -42,13 +42,6 @@ static uint32_t const ARDUINO_ESP32_OTA_HTTP_HEADER_RECEIVE_TIMEOUT_ms = 10000;
 static uint32_t const ARDUINO_ESP32_OTA_BINARY_HEADER_RECEIVE_TIMEOUT_ms = 10000;
 static uint32_t const ARDUINO_ESP32_OTA_BINARY_BYTE_RECEIVE_TIMEOUT_ms = 2000;
 
-/******************************************************************************
- * TYPEDEF
- ******************************************************************************/
-
-typedef uint8_t(*ArduinoEsp32OtaReadByteFuncPointer)(void);
-typedef void(*ArduinoEsp32OtaWriteByteFuncPointer)(uint8_t);
-
 /******************************************************************************
  * CLASS DECLARATION
  ******************************************************************************/
@@ -79,24 +72,34 @@ class Arduino_ESP32_OTA
            Arduino_ESP32_OTA();
   virtual ~Arduino_ESP32_OTA() { }
 
-  Arduino_ESP32_OTA::Error begin();
-  void setCACert (const char *rootCA);
+  Arduino_ESP32_OTA::Error begin(uint32_t magic = ARDUINO_ESP32_OTA_MAGIC);
+  void setMagic(uint32_t magic);
+  void setCACert(const char *rootCA);
   void setCACertBundle(const uint8_t * bundle);
   int download(const char * ota_url);
   uint8_t read_byte_from_network();
-  void write_byte_to_flash(uint8_t data);
+  virtual void write_byte_to_flash(uint8_t data);
   Arduino_ESP32_OTA::Error update();
   void reset();
   static bool isCapable();
 
-private:
+protected:
+
+  void otaInit();
+  void crc32Init();
+  void crc32Update(const uint8_t data);
+  void crc32Finalize();
+  bool crc32Verify();
 
+private:
   Client * _client;
   OtaHeader _ota_header;
   size_t _ota_size;
   uint32_t _crc32;
   const char * _ca_cert;
   const uint8_t * _ca_cert_bundle;
+  uint32_t _magic;
+
 };
 
 #endif /* ARDUINO_ESP32_OTA_H_ */
diff --git a/src/decompress/lzss.cpp b/src/decompress/lzss.cpp
index bce0e1c..d453c15 100644
--- a/src/decompress/lzss.cpp
+++ b/src/decompress/lzss.cpp
@@ -22,9 +22,10 @@
    GLOBAL VARIABLES
  **************************************************************************************/
 
+/* Used to bind local module function to actual class instance */
+static Arduino_ESP32_OTA * esp_ota_obj_ptr = 0;
+
 static size_t LZSS_FILE_SIZE = 0;
-static ArduinoEsp32OtaReadByteFuncPointer read_byte_fptr = 0;
-static ArduinoEsp32OtaWriteByteFuncPointer write_byte_fptr = 0;
 
 int bit_buffer = 0, bit_mask = 128;
 unsigned char buffer[N * 2];
@@ -38,7 +39,7 @@ static size_t bytes_read_fgetc = 0;
 
 void lzss_fputc(int const c)
 {
-  write_byte_fptr((uint8_t)c);
+  esp_ota_obj_ptr->write_byte_to_flash((uint8_t)c);
   
   /* write byte callback */
   bytes_written_fputc++;
@@ -56,7 +57,7 @@ int lzss_fgetc()
     return LZSS_EOF;
 
   /* read byte callback */
-  uint8_t const c = read_byte_fptr();
+  uint8_t const c = esp_ota_obj_ptr->read_byte_from_network();
   bytes_read_fgetc++;
 
   return c;
@@ -157,10 +158,9 @@ void lzss_decode(void)
    PUBLIC FUNCTIONS
  **************************************************************************************/
 
-int lzss_download(ArduinoEsp32OtaReadByteFuncPointer read_byte, ArduinoEsp32OtaWriteByteFuncPointer write_byte, size_t const lzss_file_size)
+int lzss_download(Arduino_ESP32_OTA * instance, size_t const lzss_file_size)
 {
-  read_byte_fptr = read_byte;
-  write_byte_fptr = write_byte;
+  esp_ota_obj_ptr = instance;
   LZSS_FILE_SIZE = lzss_file_size;
   bytes_written_fputc = 0;
   bytes_read_fgetc = 0;
diff --git a/src/decompress/lzss.h b/src/decompress/lzss.h
index 3ddc3f2..e88cf20 100644
--- a/src/decompress/lzss.h
+++ b/src/decompress/lzss.h
@@ -11,6 +11,6 @@
    FUNCTION DEFINITION
  **************************************************************************************/
 
-int lzss_download(ArduinoEsp32OtaReadByteFuncPointer read_byte, ArduinoEsp32OtaWriteByteFuncPointer write_byte, size_t const lzss_file_size);
+int lzss_download(Arduino_ESP32_OTA * instance, size_t const lzss_file_size);
 
 #endif /* SSU_LZSS_H_ */