  Let $T$ be a Fourier integral operator on $\R^n$ of order $-(n-1)/2$. It was
shown by Seeger, Sogge, and Stein that $T$ mapped the Hardy space $H^1$ to
$L^1$. In this note we show that $T$ is also of weak-type $(1,1)$. The main
ideas are a decomposition of $T$ into non-degenerate and degenerate components,
and a factorization of the non-degenerate portion.
