diff --git a/Doc/lib/libfuncs.tex b/Doc/lib/libfuncs.tex
index 4b925c8c366..134573464b9 100644
--- a/Doc/lib/libfuncs.tex
+++ b/Doc/lib/libfuncs.tex
@@ -125,7 +125,7 @@ class instances are callable if they have a \method{__call__()} method.
   \code{del \var{x}.\var{foobar}}.
 \end{funcdesc}
 
-\begin{funcdesc}{dir}{}
+\begin{funcdesc}{dir}{\optional{object}}
   Without arguments, return the list of names in the current local
   symbol table.  With an argument, attempts to return a list of valid
   attribute for that object.  This information is gleaned from the
diff --git a/Doc/libfuncs.tex b/Doc/libfuncs.tex
index 4b925c8c366..134573464b9 100644
--- a/Doc/libfuncs.tex
+++ b/Doc/libfuncs.tex
@@ -125,7 +125,7 @@ class instances are callable if they have a \method{__call__()} method.
   \code{del \var{x}.\var{foobar}}.
 \end{funcdesc}
 
-\begin{funcdesc}{dir}{}
+\begin{funcdesc}{dir}{\optional{object}}
   Without arguments, return the list of names in the current local
   symbol table.  With an argument, attempts to return a list of valid
   attribute for that object.  This information is gleaned from the