diff --git a/Makefile b/Makefile
index c962b64..385fafb 100644
--- a/Makefile
+++ b/Makefile
@@ -2,6 +2,8 @@ NASM = nasm
 PYTHON = python3
 QEMU = qemu-system-i386
 
+BUILDOPTS =
+
 .SUFFIXES:
 .SUFFIXES: .bin .asm .ans .wall
 
@@ -26,10 +28,10 @@ viewer.bin: ponydos.inc
 memory.bin: ponydos.inc
 
 .asm.bin:
-	$(NASM) -fbin -o $@ $<
+	$(NASM) -fbin $(BUILDOPTS) -o $@ $<
 
 .ans.wall:
-	$(PYTHON) process_wallpaper.py $@ $< 7 0 0 0
+	env BUILDOPTS='$(BUILDOPTS)' $(PYTHON) process_wallpaper.py $@ $< 7 0 0 0
 
 run: ponydos.img
 	$(QEMU) -drive file=$<,index=0,if=floppy,format=raw
diff --git a/README.md b/README.md
index afa1537..af5e297 100644
--- a/README.md
+++ b/README.md
@@ -20,6 +20,16 @@ run `make`. `make run` runs the floppy disk image `ponydos.img` with QEMU.
 By default, `qemu-system-i386` is invoked. If you want to use a different
 backend, use `make QEMU=<backend> run`.
 
+### Build options
+
+You can configure the build using build options passed to the build system using
+the `BUILDOPTS` variable, e.g. `make BUILDOPTS='-DBLINKY'`. It is advised to run
+`make clean` before changing the value of `BUILDOPTS`.
+
+* `-DBLINKY` builds an image which restricts the number of colours to 8. This is
+  for compatibility with BIOSs which use the highest bit of background colour to
+  signal that a cell should blink.
+
 ### How do I contribute?
 
 There is a model `hello.asm` file to demonstrate how best to use the
@@ -70,3 +80,7 @@ You don't.
 
 At the moment, PonyDOS is only offered as a live floppy disk image with no
 installation option, for your safety.
+
+#### How do I stop my entire desktop from blinking?
+
+Build with the [build option](#build-options) `-DBLINKY`.
diff --git a/hello.asm b/hello.asm
index b7965b0..9f60c86 100644
--- a/hello.asm
+++ b/hello.asm
@@ -2,6 +2,14 @@
 cpu 8086
 bits 16
 
+%ifdef BLINKY
+TITLEBAR_ATTRIBUTE equ 0x07
+WINDOW_ATTRIBUTE equ 0x70
+%else
+TITLEBAR_ATTRIBUTE equ 0x0f
+WINDOW_ATTRIBUTE equ 0xf0
+%endif
+
 WINDOW_STATUS_NORMAL equ 0
 WINDOW_STATUS_MOVE equ 1
 WINDOW_STATUS_RESIZE equ 2
@@ -498,12 +506,12 @@ render_window:
 	mov cx, [window_height]
 	mul cx
 	mov cx, ax
-	mov ax, 0xf000 ; Attribute is in the high byte
+	mov ax, WINDOW_ATTRIBUTE<<8 ; Attribute is in the high byte
 	rep stosw
 
 	; Set title bar to be white-on-black
 	mov di, window_data
-	mov ax, 0x0f00
+	mov ax, TITLEBAR_ATTRIBUTE<<8
 	mov cx, [window_width]
 	rep stosw
 
diff --git a/memory.asm b/memory.asm
index 3d03605..54c6de8 100644
--- a/memory.asm
+++ b/memory.asm
@@ -2,6 +2,14 @@
 cpu 8086
 bits 16
 
+%ifdef BLINKY
+TITLEBAR_ATTRIBUTE equ 0x07
+WINDOW_ATTRIBUTE equ 0x70
+%else
+TITLEBAR_ATTRIBUTE equ 0x0f
+WINDOW_ATTRIBUTE equ 0xf0
+%endif
+
 WINDOW_STATUS_NORMAL equ 0
 WINDOW_STATUS_MOVE equ 1
 
@@ -572,9 +580,9 @@ window_status db WINDOW_STATUS_NORMAL
 window_move_x_offset dw 0
 
 window_data:
-	db 'U', 0x0f, 's', 0x0f, 'a', 0x0f, 'g', 0x0f, 'e', 0x0f
-	times 10-5-1 db 0x00, 0x0f
-	db 'x', 0x0f
-	db '0', 0xf0, '1', 0xf0, '2', 0xf0, '3', 0xf0, '4', 0xf0, '5'
-	db 0xf0, '6', 0xf0, '7', 0xf0, '8', 0xf0, '9', 0xf0
-	.indicators: times 10 db 0x00, 0xf0
+	db 'U', TITLEBAR_ATTRIBUTE, 's', TITLEBAR_ATTRIBUTE, 'a', TITLEBAR_ATTRIBUTE, 'g', TITLEBAR_ATTRIBUTE, 'e', TITLEBAR_ATTRIBUTE
+	times 10-5-1 db 0x00, TITLEBAR_ATTRIBUTE
+	db 'x', TITLEBAR_ATTRIBUTE
+	db '0', WINDOW_ATTRIBUTE, '1', WINDOW_ATTRIBUTE, '2', WINDOW_ATTRIBUTE, '3', WINDOW_ATTRIBUTE, '4', WINDOW_ATTRIBUTE, '5'
+	db WINDOW_ATTRIBUTE, '6', WINDOW_ATTRIBUTE, '7', WINDOW_ATTRIBUTE, '8', WINDOW_ATTRIBUTE, '9', WINDOW_ATTRIBUTE
+	.indicators: times 10 db 0x00, WINDOW_ATTRIBUTE
diff --git a/process_wallpaper.py b/process_wallpaper.py
index f92ab47..dfc346c 100644
--- a/process_wallpaper.py
+++ b/process_wallpaper.py
@@ -1,3 +1,4 @@
+import os
 import sys
 
 from collections import namedtuple
@@ -14,6 +15,15 @@ if len(sys.argv) != 7:
 	print("Usage: {sys.argv[0]} outfile infile default_fgcolor default_bgcolor origin_x origin_y", file=sys.stderr)
 	sys.exit(1)
 
+blinky_vgamode = False
+if 'BUILDOPTS' in os.environ:
+	for opt in os.environ['BUILDOPTS'].split():
+		if opt == '-DBLINKY':
+			blinky_vgamode = True
+		else:
+			print(f"Error: Unrecognized build option {opt}", file=sys.stderr)
+			sys.exit(1)
+
 outfile = sys.argv[1]
 infile = sys.argv[2]
 
@@ -118,5 +128,14 @@ with open(outfile, 'wb') as f:
 	for y in range(HEIGHT):
 		for x in range(WIDTH):
 			fgcolor, bgcolor, bold = attributes[x][y]
+			fgcolor = fgcolor | (8 if bold else 0)
+			if blinky_vgamode:
+				# VGA mode can be set up so that the highest
+				# bit of the bg colour marks that the cell
+				# should blink instead of intensity
+				# Restrict the colours (including foreground
+				# to account for swapping of the two) to 0…7
+				fgcolor = fgcolor & 0x7
+				bgcolor = bgcolor & 0x7
 			char = chars[x][y]
-			f.write(bytes([char, (bgcolor<<4) | fgcolor | (8 if bold else 0)]))
+			f.write(bytes([char, (bgcolor<<4) | fgcolor]))
diff --git a/shell.asm b/shell.asm
index dcacbb5..5ef1c6e 100644
--- a/shell.asm
+++ b/shell.asm
@@ -1,4 +1,16 @@
 %include "ponydos.inc"
+cpu 8086
+bits 16
+
+%ifdef BLINKY
+TITLEBAR_ATTRIBUTE equ 0x07
+WINDOW_ATTRIBUTE equ 0x70
+DISK_ATTRIBUTE equ 0x07
+%else
+TITLEBAR_ATTRIBUTE equ 0x0f
+WINDOW_ATTRIBUTE equ 0xf0
+DISK_ATTRIBUTE equ 0x0f
+%endif
 
 struc window
 	.next resw 1
@@ -637,7 +649,7 @@ launch:
 show_launch_error:
 	mov di, launch_error_dialog.filename
 	mov cx, FS_DIRENT_NAME_SIZE-1
-	mov ah, 0xf0
+	mov ah, WINDOW_ATTRIBUTE
 	.copy:
 		lodsb
 		test al, al
@@ -937,11 +949,11 @@ render_file_window:
 	mov es, ax
 	mov di, [si + window.data]
 	mov cx, [si + window.width]
-	mov ax, 0x0f00
+	mov ax, TITLEBAR_ATTRIBUTE<<8
 	rep stosw
 
 	mov cx, (ROWS-1)*COLUMNS
-	mov ax, 0xf000
+	mov ax, WINDOW_ATTRIBUTE<<8
 	rep stosw
 
 	mov di, [si + window.data]
@@ -1225,28 +1237,28 @@ viewer_file_name db 'viewer.bin', 0
 ; ------------------------------------------------------------------
 
 disk_icon:
-	db 0x00, 0x0f, 0x00, 0x0f, 0x00, 0x0f, 0x00, 0x0f, 0x00, 0x0f
-	db 0x00, 0x0f, 0x00, 0x0f, 0x09, 0x0f, 0x00, 0x0f, 0x00, 0x0f
-	db 0x00, 0x0f, 0x00, 0x0f, '|', 0x0f, 0x00, 0x0f, 0x00, 0x0f
+	db 0x00, DISK_ATTRIBUTE, 0x00, DISK_ATTRIBUTE, 0x00, DISK_ATTRIBUTE, 0x00, DISK_ATTRIBUTE, 0x00, DISK_ATTRIBUTE
+	db 0x00, DISK_ATTRIBUTE, 0x00, DISK_ATTRIBUTE, 0x09, DISK_ATTRIBUTE, 0x00, DISK_ATTRIBUTE, 0x00, DISK_ATTRIBUTE
+	db 0x00, DISK_ATTRIBUTE, 0x00, DISK_ATTRIBUTE, '|', DISK_ATTRIBUTE, 0x00, DISK_ATTRIBUTE, 0x00, DISK_ATTRIBUTE
 
 oom_error_dialog:
-	db 'E', 0x0f, 'r', 0x0f, 'r', 0x0f, 'o', 0x0f, 'r', 0x0f
-	times 13-5-1 db 0x00, 0x0f
-	db 'x', 0x0f
-	db 'O', 0xf0, 'u', 0xf0, 't', 0xf0, ' ', 0xf0, 'o', 0xf0, 'f', 0xf0
-	db ' ', 0xf0, 'm', 0xf0, 'e', 0xf0, 'm', 0xf0, 'o', 0xf0, 'r', 0xf0
-	db 'y', 0xf0
+	db 'E', TITLEBAR_ATTRIBUTE, 'r', TITLEBAR_ATTRIBUTE, 'r', TITLEBAR_ATTRIBUTE, 'o', TITLEBAR_ATTRIBUTE, 'r', TITLEBAR_ATTRIBUTE
+	times 13-5-1 db 0x00, TITLEBAR_ATTRIBUTE
+	db 'x', TITLEBAR_ATTRIBUTE
+	db 'O', WINDOW_ATTRIBUTE, 'u', WINDOW_ATTRIBUTE, 't', WINDOW_ATTRIBUTE, ' ', WINDOW_ATTRIBUTE, 'o', WINDOW_ATTRIBUTE, 'f', WINDOW_ATTRIBUTE
+	db ' ', WINDOW_ATTRIBUTE, 'm', WINDOW_ATTRIBUTE, 'e', WINDOW_ATTRIBUTE, 'm', WINDOW_ATTRIBUTE, 'o', WINDOW_ATTRIBUTE, 'r', WINDOW_ATTRIBUTE
+	db 'y', WINDOW_ATTRIBUTE
 
 launch_error_dialog:
-	db 'E', 0x0f, 'r', 0x0f, 'r', 0x0f, 'o', 0x0f, 'r', 0x0f
-	times FS_DIRENT_NAME_SIZE-1-5-1 db 0x00, 0x0f
-	db 'x', 0x0f
-	db 'C', 0xf0, 'a', 0xf0, 'n', 0xf0, 'n', 0xf0, 'o', 0xf0, 't', 0xf0
-	db ' ', 0xf0, 'l', 0xf0, 'a', 0xf0, 'u', 0xf0, 'n', 0xf0, 'c', 0xf0
-	db 'h', 0xf0, ' ', 0xf0, 'f', 0xf0, 'i', 0xf0, 'l', 0xf0, 'e', 0xf0
-	db ':', 0xf0
-	times FS_DIRENT_NAME_SIZE-1-19 db 0x00, 0xf0
-	.filename times FS_DIRENT_NAME_SIZE-1 db 0x00, 0xf0
+	db 'E', TITLEBAR_ATTRIBUTE, 'r', TITLEBAR_ATTRIBUTE, 'r', TITLEBAR_ATTRIBUTE, 'o', TITLEBAR_ATTRIBUTE, 'r', TITLEBAR_ATTRIBUTE
+	times FS_DIRENT_NAME_SIZE-1-5-1 db 0x00, TITLEBAR_ATTRIBUTE
+	db 'x', TITLEBAR_ATTRIBUTE
+	db 'C', WINDOW_ATTRIBUTE, 'a', WINDOW_ATTRIBUTE, 'n', WINDOW_ATTRIBUTE, 'n', WINDOW_ATTRIBUTE, 'o', WINDOW_ATTRIBUTE, 't', WINDOW_ATTRIBUTE
+	db ' ', WINDOW_ATTRIBUTE, 'l', WINDOW_ATTRIBUTE, 'a', WINDOW_ATTRIBUTE, 'u', WINDOW_ATTRIBUTE, 'n', WINDOW_ATTRIBUTE, 'c', WINDOW_ATTRIBUTE
+	db 'h', WINDOW_ATTRIBUTE, ' ', WINDOW_ATTRIBUTE, 'f', WINDOW_ATTRIBUTE, 'i', WINDOW_ATTRIBUTE, 'l', WINDOW_ATTRIBUTE, 'e', WINDOW_ATTRIBUTE
+	db ':', WINDOW_ATTRIBUTE
+	times FS_DIRENT_NAME_SIZE-1-19 db 0x00, WINDOW_ATTRIBUTE
+	.filename times FS_DIRENT_NAME_SIZE-1 db 0x00, WINDOW_ATTRIBUTE
 
 windows:
 	times window.size db 0
diff --git a/viewer.asm b/viewer.asm
index acfa540..bb8041c 100644
--- a/viewer.asm
+++ b/viewer.asm
@@ -2,6 +2,19 @@
 cpu 8086
 bits 16
 
+%ifdef BLINKY
+TITLEBAR_ATTRIBUTE equ 0x07
+WINDOW_ATTRIBUTE equ 0x70
+CANCEL_ATTRIBUTE equ 0x07
+%else
+TITLEBAR_ATTRIBUTE equ 0x0f
+WINDOW_ATTRIBUTE equ 0xf0
+CANCEL_ATTRIBUTE equ 0x8f
+%endif
+OK_ATTRIBUTE equ 0x20
+OPEN_DIALOG_ATTRIBUTE equ 0x70
+FILENAME_ATTRIBUTE equ WINDOW_ATTRIBUTE
+
 WINDOW_STATUS_NORMAL equ 0
 WINDOW_STATUS_MOVE equ 1
 WINDOW_STATUS_RESIZE equ 2
@@ -591,14 +604,14 @@ event_click:
 		mov bx, ax
 		inc bx
 
-		cmp byte [bx], CANCEL_COLOR
+		cmp byte [bx], CANCEL_ATTRIBUTE
 		jne .not_cancel
 		.cancel:
 			call unhook_self_from_window_chain
 			mov byte [exiting], 1
 			jmp .end
 		.not_cancel:
-		cmp byte [bx], OK_COLOR
+		cmp byte [bx], OK_ATTRIBUTE
 		jne .not_ok
 		.ok:
 			call filename_ok
@@ -921,12 +934,12 @@ render_window:
 	mov cx, [window.height]
 	mul cx
 	mov cx, ax
-	mov ax, 0xf000 ; Attribute is in the high byte
+	mov ax, WINDOW_ATTRIBUTE<<8 ; Attribute is in the high byte
 	rep stosw
 
 	; Set title bar to be white-on-black
 	mov di, text_window_data
-	mov ax, 0x0f00
+	mov ax, TITLEBAR_ATTRIBUTE<<8
 	mov cx, [window.width]
 	rep stosw
 
@@ -1233,46 +1246,44 @@ cur_filename_address dw filename_window_data.filename
 file_opened db 0
 
 ; pre-built windows
-CANCEL_COLOR equ 0x8f
-OK_COLOR equ 0x20
 filename_window_data:
 	; header
-	db 'V', 0x0f, 'i', 0x0f, 'e', 0x0f, 'w', 0x0f, 'e', 0x0f, 'r', 0x0f
-	times FS_DIRENT_NAME_SIZE + 2 - 7 db 0, 0x0f
-	db 'x', 0x0f
+	db 'V', TITLEBAR_ATTRIBUTE, 'i', TITLEBAR_ATTRIBUTE, 'e', TITLEBAR_ATTRIBUTE, 'w', TITLEBAR_ATTRIBUTE, 'e', TITLEBAR_ATTRIBUTE, 'r', TITLEBAR_ATTRIBUTE
+	times FS_DIRENT_NAME_SIZE + 2 - 7 db 0, TITLEBAR_ATTRIBUTE
+	db 'x', TITLEBAR_ATTRIBUTE
 	; blank line
-	times FS_DIRENT_NAME_SIZE + 2 db 0, 0x70
+	times FS_DIRENT_NAME_SIZE + 2 db 0, OPEN_DIALOG_ATTRIBUTE
 	; filename
-	db 0, 0x70
+	db 0, OPEN_DIALOG_ATTRIBUTE
 	.filename:
-	times FS_DIRENT_NAME_SIZE db 0, 0xf0
-	db 0, 0x70
+	times FS_DIRENT_NAME_SIZE db 0, FILENAME_ATTRIBUTE
+	db 0, OPEN_DIALOG_ATTRIBUTE
 	; blank line
-	times FS_DIRENT_NAME_SIZE + 2 db 0, 0x70
+	times FS_DIRENT_NAME_SIZE + 2 db 0, OPEN_DIALOG_ATTRIBUTE
 	; buttons line
-	times 7 db 0, 0x70
-	db 0, 0x8f, 'C', 0x8f, 'a', 0x8f, 'n', 0x8f, 'c', 0x8f, 'e', 0x8f, 'l', 0x8f, 0, 0x8f
-	times 5 db 0, 0x70
-	db 0, 0x20, 'O', 0x20, 'K', 0x20, 0x, 0x20
-	times 8 db 0, 0x70
+	times 7 db 0, OPEN_DIALOG_ATTRIBUTE
+	db 0, CANCEL_ATTRIBUTE, 'C', CANCEL_ATTRIBUTE, 'a', CANCEL_ATTRIBUTE, 'n', CANCEL_ATTRIBUTE, 'c', CANCEL_ATTRIBUTE, 'e', CANCEL_ATTRIBUTE, 'l', CANCEL_ATTRIBUTE, 0, CANCEL_ATTRIBUTE
+	times 5 db 0, OPEN_DIALOG_ATTRIBUTE
+	db 0, OK_ATTRIBUTE, 'O', OK_ATTRIBUTE, 'K', OK_ATTRIBUTE, 0x, OK_ATTRIBUTE
+	times 8 db 0, OPEN_DIALOG_ATTRIBUTE
 	; blank line
-	times FS_DIRENT_NAME_SIZE + 2 db 0, 0x70
+	times FS_DIRENT_NAME_SIZE + 2 db 0, OPEN_DIALOG_ATTRIBUTE
 
 oom_window_data:
-	db 'E', 0x0f, 'r', 0x0f, 'r', 0x0f, 'o', 0x0f, 'r', 0x0f
-	times 13-5-1 db 0x00, 0x0f
-	db 'x', 0x0f
-	db 'O', 0xf0, 'u', 0xf0, 't', 0xf0, ' ', 0xf0, 'o', 0xf0, 'f', 0xf0
-	db ' ', 0xf0, 'm', 0xf0, 'e', 0xf0, 'm', 0xf0, 'o', 0xf0, 'r', 0xf0
-	db 'y', 0xf0
+	db 'E', TITLEBAR_ATTRIBUTE, 'r', TITLEBAR_ATTRIBUTE, 'r', TITLEBAR_ATTRIBUTE, 'o', TITLEBAR_ATTRIBUTE, 'r', TITLEBAR_ATTRIBUTE
+	times 13-5-1 db 0x00, TITLEBAR_ATTRIBUTE
+	db 'x', TITLEBAR_ATTRIBUTE
+	db 'O', WINDOW_ATTRIBUTE, 'u', WINDOW_ATTRIBUTE, 't', WINDOW_ATTRIBUTE, ' ', WINDOW_ATTRIBUTE, 'o', WINDOW_ATTRIBUTE, 'f', WINDOW_ATTRIBUTE
+	db ' ', WINDOW_ATTRIBUTE, 'm', WINDOW_ATTRIBUTE, 'e', WINDOW_ATTRIBUTE, 'm', WINDOW_ATTRIBUTE, 'o', WINDOW_ATTRIBUTE, 'r', WINDOW_ATTRIBUTE
+	db 'y', WINDOW_ATTRIBUTE
 
 ood_window_data:
-	db 'E', 0x0f, 'r', 0x0f, 'r', 0x0f, 'o', 0x0f, 'r', 0x0f
-	times 17-5-1 db 0x00, 0x0f
-	db 'x', 0x0f
-	db 'O', 0xf0, 'u', 0xf0, 't', 0xf0, ' ', 0xf0, 'o', 0xf0, 'f', 0xf0
-	db ' ', 0xf0, 'd', 0xf0, 'i', 0xf0, 's', 0xf0, 'k', 0xf0, ' ', 0xf0
-	db 's', 0xf0, 'p', 0xf0, 'a', 0xf0, 'c', 0xf0, 'e', 0xf0
+	db 'E', TITLEBAR_ATTRIBUTE, 'r', TITLEBAR_ATTRIBUTE, 'r', TITLEBAR_ATTRIBUTE, 'o', TITLEBAR_ATTRIBUTE, 'r', TITLEBAR_ATTRIBUTE
+	times 17-5-1 db 0x00, TITLEBAR_ATTRIBUTE
+	db 'x', TITLEBAR_ATTRIBUTE
+	db 'O', WINDOW_ATTRIBUTE, 'u', WINDOW_ATTRIBUTE, 't', WINDOW_ATTRIBUTE, ' ', WINDOW_ATTRIBUTE, 'o', WINDOW_ATTRIBUTE, 'f', WINDOW_ATTRIBUTE
+	db ' ', WINDOW_ATTRIBUTE, 'd', WINDOW_ATTRIBUTE, 'i', WINDOW_ATTRIBUTE, 's', WINDOW_ATTRIBUTE, 'k', WINDOW_ATTRIBUTE, ' ', WINDOW_ATTRIBUTE
+	db 's', WINDOW_ATTRIBUTE, 'p', WINDOW_ATTRIBUTE, 'a', WINDOW_ATTRIBUTE, 'c', WINDOW_ATTRIBUTE, 'e', WINDOW_ATTRIBUTE
 
 section .bss
 text_window_data resw ROWS*COLUMNS