diff --git a/x86/boot.c b/x86/boot.c
index 9383824..c434030 100644
--- a/x86/boot.c
+++ b/x86/boot.c
@@ -25,10 +25,10 @@ bool kvm__load_firmware(struct kvm *kvm, const char *firmware_filename)
 	if (fstat(fd, &st))
 		return false;
 
-	if (st.st_size > MB_BIOS_SIZE)
+	if (st.st_size > MB_FIRMWARE_BIOS_SIZE)
 		die("firmware image %s is too big to fit in memory (%lu KB).\n", firmware_filename, st.st_size / 1024);
 
-	p = guest_flat_to_host(kvm, MB_BIOS_BEGIN);
+	p = guest_flat_to_host(kvm, MB_FIRMWARE_BIOS_BEGIN);
 
 	while ((nr = read(fd, p, st.st_size)) > 0)
 		p += nr;
diff --git a/x86/include/kvm/bios.h b/x86/include/kvm/bios.h
index 9d677ae..ec7ed71 100644
--- a/x86/include/kvm/bios.h
+++ b/x86/include/kvm/bios.h
@@ -10,6 +10,7 @@
  * EBDA area				0x0009FC00 0x0009FFFF
  * VIDEO RAM				0x000A0000 0x000BFFFF
  * VIDEO ROM (BIOS)			0x000C0000 0x000C7FFF
+ * ROMs & unus. space (mapped hw & misc)0x000C8000 0x000EFFFF 160 KiB (typically)
  * Motherboard BIOS			0x000F0000 0x000FFFFF
  * Extended Memory			0x00100000 0xFEBFFFFF
  * Reserved (configs, ACPI, PnP, etc)	0xFEC00000 0xFFFFFFFF
@@ -26,9 +27,12 @@
 
 #define E820_MAP_START			EBDA_START
 
-#define MB_BIOS_BEGIN			0x000e0000
+#define MB_BIOS_BEGIN			0x000f0000
+#define MB_FIRMWARE_BIOS_BEGIN		0x000e0000
 #define MB_BIOS_END			0x000fffff
+
 #define MB_BIOS_SIZE			(MB_BIOS_END - MB_BIOS_BEGIN + 1)
+#define MB_FIRMWARE_BIOS_SIZE		(MB_BIOS_END - MB_FIRMWARE_BIOS_BEGIN + 1)
 
 #define VGA_RAM_BEGIN			0x000a0000
 #define VGA_RAM_END			0x000bffff