diff --git a/examples/platforms/nrf52811/flash_nosd.c b/examples/platforms/nrf52811/flash_nosd.c
index 5a8854899..561eb0886 100644
--- a/examples/platforms/nrf52811/flash_nosd.c
+++ b/examples/platforms/nrf52811/flash_nosd.c
@@ -51,7 +51,7 @@ bool nrf5FlashIsBusy(void)
     return NRF_NVMC->READY != NVMC_READY_READY_Ready;
 }
 
-uint32_t nrf5FlashWrite(uint32_t aAddress, uint8_t *aData, uint32_t aSize)
+uint32_t nrf5FlashWrite(uint32_t aAddress, const uint8_t *aData, uint32_t aSize)
 {
     nrf_nvmc_write_bytes(aAddress, aData, aSize);
     return aSize;
diff --git a/examples/platforms/nrf52811/platform-nrf5.h b/examples/platforms/nrf52811/platform-nrf5.h
index 88dd7a996..3fc4a6039 100644
--- a/examples/platforms/nrf52811/platform-nrf5.h
+++ b/examples/platforms/nrf52811/platform-nrf5.h
@@ -170,7 +170,7 @@ bool nrf5FlashIsBusy(void);
  * Function for writing data into flash.
  *
  */
-uint32_t nrf5FlashWrite(uint32_t aAddress, uint8_t *aData, uint32_t aSize);
+uint32_t nrf5FlashWrite(uint32_t aAddress, const uint8_t *aData, uint32_t aSize);
 
 /**
  * Initialization of temperature controller.
diff --git a/examples/platforms/nrf52840/flash_nosd.c b/examples/platforms/nrf52840/flash_nosd.c
index 784600abe..4e9b1f1a1 100644
--- a/examples/platforms/nrf52840/flash_nosd.c
+++ b/examples/platforms/nrf52840/flash_nosd.c
@@ -51,7 +51,7 @@ bool nrf5FlashIsBusy(void)
     return NRF_NVMC->READY != NVMC_READY_READY_Ready;
 }
 
-uint32_t nrf5FlashWrite(uint32_t aAddress, uint8_t *aData, uint32_t aSize)
+uint32_t nrf5FlashWrite(uint32_t aAddress, const uint8_t *aData, uint32_t aSize)
 {
     nrf_nvmc_write_bytes(aAddress, aData, aSize);
     return aSize;
diff --git a/examples/platforms/nrf52840/flash_sd.c b/examples/platforms/nrf52840/flash_sd.c
index 659635c10..a5ab0abfe 100644
--- a/examples/platforms/nrf52840/flash_sd.c
+++ b/examples/platforms/nrf52840/flash_sd.c
@@ -78,7 +78,7 @@ void nrf5SdSocFlashProcess(uint32_t aEvtId)
     }
 }
 
-static otError sdFlashSingleWrite(uint32_t aAddress, uint8_t *aData, uint32_t aSize)
+static otError sdFlashSingleWrite(uint32_t aAddress, const uint8_t *aData, uint32_t aSize)
 {
     uint32_t retval;
     uint32_t startTime = otPlatAlarmMilliGetNow();
@@ -149,7 +149,7 @@ bool nrf5FlashIsBusy(void)
     return sFlashStatus != FLASH_STATUS_IDLE;
 }
 
-uint32_t nrf5FlashWrite(uint32_t aAddress, uint8_t *aData, uint32_t aSize)
+uint32_t nrf5FlashWrite(uint32_t aAddress, const uint8_t *aData, uint32_t aSize)
 {
     otError  error = OT_ERROR_NONE;
     uint32_t result = 0;
diff --git a/examples/platforms/nrf52840/platform-nrf5.h b/examples/platforms/nrf52840/platform-nrf5.h
index 03d24cb91..afc06791e 100644
--- a/examples/platforms/nrf52840/platform-nrf5.h
+++ b/examples/platforms/nrf52840/platform-nrf5.h
@@ -188,7 +188,7 @@ bool nrf5FlashIsBusy(void);
  * Function for writing data into flash.
  *
  */
-uint32_t nrf5FlashWrite(uint32_t aAddress, uint8_t *aData, uint32_t aSize);
+uint32_t nrf5FlashWrite(uint32_t aAddress, const uint8_t *aData, uint32_t aSize);
 
 /**
  * Initialization of temperature controller.