diff --git a/examples/knx-bme680/knx-bme680.ino b/examples/knx-bme680/knx-bme680.ino
index b6deb6d..f10a723 100644
--- a/examples/knx-bme680/knx-bme680.ino
+++ b/examples/knx-bme680/knx-bme680.ino
@@ -25,7 +25,7 @@
 void checkIaqSensorStatus(void);
 void errLeds(void);
 uint8_t* saveBme680State(uint8_t* buffer);
-uint8_t* loadBme680State(uint8_t* buffer);
+const uint8_t* loadBme680State(const uint8_t* buffer);
 void triggerCallback(GroupObject& go);
 void updateState();
 
@@ -214,7 +214,7 @@ void errLeds(void)
     delay(100);
 }
 
-uint8_t* loadBme680State(uint8_t* buffer)
+const uint8_t* loadBme680State(const uint8_t* buffer)
 {
     // Existing state in EEPROM
     Serial.println("Reading state from EEPROM");
diff --git a/src/esp32_platform.cpp b/src/esp32_platform.cpp
index 585464f..5c28ee1 100644
--- a/src/esp32_platform.cpp
+++ b/src/esp32_platform.cpp
@@ -104,6 +104,7 @@ uint8_t * Esp32Platform::getEepromBuffer(uint16_t size)
 
 void Esp32Platform::commitToEeprom()
 {
+    EEPROM.getDataPtr(); // trigger dirty flag in EEPROM lib to make sure data will be written to flash
     EEPROM.commit();
 }
 
diff --git a/src/knx_facade.h b/src/knx_facade.h
index e858440..e0cecab 100644
--- a/src/knx_facade.h
+++ b/src/knx_facade.h
@@ -40,7 +40,8 @@
     #endif
 #endif
 
-typedef uint8_t* (*SaveRestoreCallback)(uint8_t* buffer);
+typedef const uint8_t* (*RestoreCallback)(const uint8_t* buffer);
+typedef uint8_t* (*SaveCallback)(uint8_t* buffer);
 typedef void (*IsrFunctionPtr)();
  
 template <class P, class B> class KnxFacade : private SaveRestore
@@ -266,12 +267,12 @@ template <class P, class B> class KnxFacade : private SaveRestore
         _progButtonISRFuncPtr = progButtonISRFuncPtr;
     }
 
-    void setSaveCallback(SaveRestoreCallback func)
+    void setSaveCallback(SaveCallback func)
     {
         _saveCallback = func;
     }
 
-    void setRestoreCallback(SaveRestoreCallback func)
+    void setRestoreCallback(RestoreCallback func)
     {
         _restoreCallback = func;
     }
@@ -336,8 +337,8 @@ template <class P, class B> class KnxFacade : private SaveRestore
     uint32_t _ledPin = LED_BUILTIN;
     uint32_t _buttonPinInterruptOn = RISING;
     uint32_t _buttonPin = 0;
-    SaveRestoreCallback _saveCallback = 0;
-    SaveRestoreCallback _restoreCallback = 0;
+    SaveCallback _saveCallback = 0;
+    RestoreCallback _restoreCallback = 0;
     volatile bool _toggleProgMode = false;
     bool _progLedState = false;
     uint16_t _saveSize = 0;
@@ -351,7 +352,7 @@ template <class P, class B> class KnxFacade : private SaveRestore
         return buffer;
     }
 
-    uint8_t* restore(uint8_t* buffer)
+    const uint8_t* restore(const uint8_t* buffer)
     {
         if (_restoreCallback != 0)
             return _restoreCallback(buffer);