Why does my Macro get expanded 8 times?

[David Vinayak Wallace <Gumby@MCC.COM>]

    Date: Wed, 6 Jul 88 16:40 EDT
    From: Daniel L. Weinreb <DLW@ALDERAAN.SCRC.Symbolics.COM>

    When the compiler sees the NIL, it is obvious that the NIL is not a
    declaration, and is not a documentation string.

I guess the compiler is smarter than me!