diff --git a/Doc/lib/librotor.tex b/Doc/lib/librotor.tex
index af2a283..c333686 100644
--- a/Doc/lib/librotor.tex
+++ b/Doc/lib/librotor.tex
@@ -35,9 +35,8 @@
 Rotor objects have the following methods:
 
 \renewcommand{\indexsubitem}{(rotor method)}
-\begin{funcdesc}{setkey}{\optional{key}}
-Sets the rotor's key to \var{key}.  If \var{key} is not given, this
-function does nothing\footnote{This is for backwards compatibility.}.
+\begin{funcdesc}{setkey}{key}
+Sets the rotor's key to \var{key}.
 \end{funcdesc}
 
 \begin{funcdesc}{encrypt}{plaintext}
diff --git a/Doc/librotor.tex b/Doc/librotor.tex
index af2a283..c333686 100644
--- a/Doc/librotor.tex
+++ b/Doc/librotor.tex
@@ -35,9 +35,8 @@
 Rotor objects have the following methods:
 
 \renewcommand{\indexsubitem}{(rotor method)}
-\begin{funcdesc}{setkey}{\optional{key}}
-Sets the rotor's key to \var{key}.  If \var{key} is not given, this
-function does nothing\footnote{This is for backwards compatibility.}.
+\begin{funcdesc}{setkey}{key}
+Sets the rotor's key to \var{key}.
 \end{funcdesc}
 
 \begin{funcdesc}{encrypt}{plaintext}