diff --git a/AUTHORS b/AUTHORS
index 1e5c78d..d63138a 100644
--- a/AUTHORS
+++ b/AUTHORS
@@ -4,6 +4,10 @@ Anthony Romano:
 	src/main.c
 	src/mod.c
 
+Jeremy Drake:
+    Modified:
+	regnual/regnual.c
+
 Kaz Kojima:
     Added STM32 Primer2 support.
 
diff --git a/ChangeLog b/ChangeLog
index 115fcc2..2813c84 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2017-08-03  Jeremy Drake <jeremydrake+gnuk@eacceleration.com>
+
+	* regnual/regnual.c (main): Allow compile time
+	flash size definition by STM32F103_OVERRIDE_FLASH_SIZE_KB.
+
 2017-08-02  Jeremy Drake  <jeremydrake+gnuk@eacceleration.com>
 
 	* src/flash.c (flash_terminate): Erase Certificate DO, too.
diff --git a/regnual/regnual.c b/regnual/regnual.c
index e472669..1ee5c56 100644
--- a/regnual/regnual.c
+++ b/regnual/regnual.c
@@ -1,7 +1,7 @@
 /*
  * regnual.c -- Firmware installation for STM32F103 Flash ROM
  *
- * Copyright (C) 2012, 2013, 2015, 2016
+ * Copyright (C) 2012, 2013, 2015, 2016, 2017
  *               Free Software Initiative of Japan
  * Author: NIIBE Yutaka <gniibe@fsij.org>
  *
@@ -365,7 +365,11 @@ main (int argc, char *argv[])
 
   set_led (0);
 
+#if defined(STM32F103_OVERRIDE_FLASH_SIZE_KB)
+  flash_end = FLASH_START_ADDR + STM32F103_OVERRIDE_FLASH_SIZE_KB*1024;
+#else
   flash_end = FLASH_START_ADDR + (*FLASH_SIZE_REG)*1024;
+#endif
 
   /*
    * NVIC interrupt priority was set by Gnuk.