diff --git a/Doc/lib/libasyncore.tex b/Doc/lib/libasyncore.tex
index cce0d50..66998d1 100644
--- a/Doc/lib/libasyncore.tex
+++ b/Doc/lib/libasyncore.tex
@@ -136,7 +136,7 @@
   Read at most \var{buffer_size} bytes from the socket.
 \end{methoddesc}
 
-\begin{methoddesc}{listen}{\optional{backlog}}
+\begin{methoddesc}{listen}{backlog}
   Listen for connections made to the socket.  The \var{backlog}
   argument specifies the maximum number of queued connections
   and should be at least 1; the maximum value is