diff --git a/doc/pdflayout.sty b/doc/pdflayout.sty
index 1b421a1ce..02725e090 100644
--- a/doc/pdflayout.sty
+++ b/doc/pdflayout.sty
@@ -31,6 +31,7 @@
     \else\if1#1 % Letter
       \pdfpagewidth=8.5in
       \pdfpageheight=11in
+      \letterpaper=1
     \fi\fi
     \if l#2 % Landscape
       \edef\oldwidth{\the\pdfpagewidth}