diff --git a/doc/thrift.tex b/doc/thrift.tex
index 17766b5..082be62 100644
--- a/doc/thrift.tex
+++ b/doc/thrift.tex
@@ -8,6 +8,9 @@
 %
 % Created:      05 March 2007
 %
+% You will need a copy of sigplanconf.cls to format this document.
+% It is available at <http://www.sigplan.org/authorInformation.htm>.
+%
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