diff --git a/Doc/lib/libgettext.tex b/Doc/lib/libgettext.tex
index 043fa58..ace719f 100644
--- a/Doc/lib/libgettext.tex
+++ b/Doc/lib/libgettext.tex
@@ -216,7 +216,7 @@
 override this method to parse your format.
 \end{methoddesc}
 
-\begin{methoddesc}{NullTranslations}{add_fallback}{fallback}
+\begin{methoddesc}[NullTranslations]{add_fallback}{fallback}
 Add \var{fallback} as the fallback object for the current translation
 object. A translation object should consult the fallback if it cannot
 provide a translation for a given message.