diff --git a/Makefile b/Makefile
index 204fcdc7..a6e636d8 100644
--- a/Makefile
+++ b/Makefile
@@ -23,7 +23,7 @@ ROOT := $(patsubst %/,%,$(dir $(lastword $(MAKEFILE_LIST))))
 include $(ROOT)/make/tools.mk
 
 # MCU builds, if with _xxK then adds build with given flash size
-MCU_BUILDS := E230 F031 F051 F415 F421 G071 G071_64K L431
+MCU_BUILDS := E230 F031 F051 F415 F415_128K F421 G071 G071_64K L431
 
 # we support bootloader comms on a list of possible pins
 BOOTLOADER_PINS = PB4 PA2 PA15
diff --git a/Mcu/f415/Inc/blutil.h b/Mcu/f415/Inc/blutil.h
index 98c1ee8f..286b25e7 100644
--- a/Mcu/f415/Inc/blutil.h
+++ b/Mcu/f415/Inc/blutil.h
@@ -11,9 +11,12 @@
 #define STACK_TOP RAM_BASE+RAM_SIZE
 
 /*
-  use 32k flash
+  use 32k flash by default. We allow for 128k as well so we can test
+  2k sectors with the AT-START-F415 devel board
  */
+#ifndef BOARD_FLASH_SIZE
 #define BOARD_FLASH_SIZE 32
+#endif
 
 
 #define GPIO_PIN(n) (1U<<(n))