diff --git a/src/samd51_platform.cpp b/src/samd51_platform.cpp
index ad2b6b2..0a30973 100644
--- a/src/samd51_platform.cpp
+++ b/src/samd51_platform.cpp
@@ -1,7 +1,9 @@
-#ifdef __SAMD51__
-#include <Arduino.h>
 #include "samd51_platform.h"
+
+#ifdef __SAMD51__
+
 #include <knx/bits.h>
+#include <Arduino.h>
 
 #if KNX_FLASH_SIZE % 1024
 #error "KNX_FLASH_SIZE must be multiple of 1024"
diff --git a/src/samd51_platform.h b/src/samd51_platform.h
index 3063d08..491a63b 100644
--- a/src/samd51_platform.h
+++ b/src/samd51_platform.h
@@ -1,7 +1,8 @@
-#ifdef __SAMD51__
 #include "Arduino.h"
 #include "arduino_platform.h"
 
+#ifdef __SAMD51__
+
 class Samd51Platform : public ArduinoPlatform
 {
 public:
diff --git a/src/samd_platform.cpp b/src/samd_platform.cpp
index eb100da..be888fb 100644
--- a/src/samd_platform.cpp
+++ b/src/samd_platform.cpp
@@ -1,10 +1,10 @@
+#include "samd_platform.h"
+
 #if(defined(__SAMD21E17A__) || \
     defined(__SAMD21G18A__) || \
     defined(__SAMD21E18A__) || \
     defined(__SAMD21J18A__))
 
-#include "samd_platform.h"
-
 #include <knx/bits.h>
 
 #include <Arduino.h>
@@ -39,21 +39,11 @@ SamdPlatform::SamdPlatform( HardwareSerial* s) : ArduinoPlatform(s)
 
 uint32_t SamdPlatform::uniqueSerialNumber()
 {
-    #if defined (__SAMD51__)
-      // SAMD51 from section 9.6 of the datasheet
-      #define SERIAL_NUMBER_WORD_0	*(volatile uint32_t*)(0x008061FC)
-      #define SERIAL_NUMBER_WORD_1	*(volatile uint32_t*)(0x00806010)
-      #define SERIAL_NUMBER_WORD_2	*(volatile uint32_t*)(0x00806014)
-      #define SERIAL_NUMBER_WORD_3	*(volatile uint32_t*)(0x00806018)
-    #else
-    //#elif defined (__SAMD21E17A__) || defined(__SAMD21G18A__)  || defined(__SAMD21E18A__) || defined(__SAMD21J18A__)
-    // SAMD21 from section 9.3.3 of the datasheet
-      #define SERIAL_NUMBER_WORD_0	*(volatile uint32_t*)(0x0080A00C)
-      #define SERIAL_NUMBER_WORD_1	*(volatile uint32_t*)(0x0080A040)
-      #define SERIAL_NUMBER_WORD_2	*(volatile uint32_t*)(0x0080A044)
-      #define SERIAL_NUMBER_WORD_3	*(volatile uint32_t*)(0x0080A048)
-    #endif
-
+    #define SERIAL_NUMBER_WORD_0	*(volatile uint32_t*)(0x0080A00C)
+    #define SERIAL_NUMBER_WORD_1	*(volatile uint32_t*)(0x0080A040)
+    #define SERIAL_NUMBER_WORD_2	*(volatile uint32_t*)(0x0080A044)
+    #define SERIAL_NUMBER_WORD_3	*(volatile uint32_t*)(0x0080A048)
+    
     return SERIAL_NUMBER_WORD_0 ^ SERIAL_NUMBER_WORD_1 ^ SERIAL_NUMBER_WORD_2 ^ SERIAL_NUMBER_WORD_3;
 }