diff --git a/ports/stm/boards/thunderpack/mpconfigboard.h b/ports/stm/boards/thunderpack/mpconfigboard.h
index 270600b3c8..0b3c55819a 100644
--- a/ports/stm/boards/thunderpack/mpconfigboard.h
+++ b/ports/stm/boards/thunderpack/mpconfigboard.h
@@ -33,7 +33,7 @@
 
 // Putting the entire flash sector in the NVM byte array buffer
 // would take up too much RAM. This limits how much of the sector we use.
-#define NVM_BYTEARRAY_BUFFER_LEN           512
+#define NVM_BYTEARRAY_BUFFER_SIZE           512
 
 // Flash config
 #define FLASH_SIZE                         (0x80000)
diff --git a/ports/stm/common-hal/microcontroller/__init__.c b/ports/stm/common-hal/microcontroller/__init__.c
index b69407eff7..d407ecfe50 100644
--- a/ports/stm/common-hal/microcontroller/__init__.c
+++ b/ports/stm/common-hal/microcontroller/__init__.c
@@ -116,7 +116,7 @@ const nvm_bytearray_obj_t common_hal_mcu_nvm_obj = {
     .base = {
         .type = &nvm_bytearray_type,
     },
-    .len = NVM_BYTEARRAY_BUFFER_LEN,
+    .len = NVM_BYTEARRAY_BUFFER_SIZE,
     .start_address = (uint8_t*) (CIRCUITPY_INTERNAL_NVM_START_ADDR)
 };
 #endif
diff --git a/ports/stm/common-hal/nvm/ByteArray.h b/ports/stm/common-hal/nvm/ByteArray.h
index 0d7ecf6ab7..b6ea36de3f 100644
--- a/ports/stm/common-hal/nvm/ByteArray.h
+++ b/ports/stm/common-hal/nvm/ByteArray.h
@@ -32,8 +32,8 @@
 // STM flash is saved in sectors (not pages), at a minimum size of 16k.
 // To limit the RAM usage during writing, we want to set a smaller
 // maximum value.
-#ifndef NVM_BYTEARRAY_BUFFER_LEN
-#define NVM_BYTEARRAY_BUFFER_LEN 512
+#ifndef NVM_BYTEARRAY_BUFFER_SIZE
+#define NVM_BYTEARRAY_BUFFER_SIZE 512
 #endif
 
 typedef struct {