diff --git a/ponydos.asm b/ponydos.asm
index 157fa1a..e98f7ab 100644
--- a/ponydos.asm
+++ b/ponydos.asm
@@ -214,9 +214,7 @@ flip_mouse_cursor:
 
 	; Swap foreground and background colours
 	inc bx
-	mov al, [es:bx]
-	ror al, 4
-	mov [es:bx], al
+	ror byte [es:bx], 4
 
 	popa
 	ret