diff --git a/Doc/lib/libnntplib.tex b/Doc/lib/libnntplib.tex
index f2fdebdf310..b02f142d0d8 100644
--- a/Doc/lib/libnntplib.tex
+++ b/Doc/lib/libnntplib.tex
@@ -2,6 +2,7 @@
 \label{module-nntplib}
 \stmodindex{nntplib}
 \indexii{NNTP}{protocol}
+\index{Network News Transfer Protocol}
 
 
 This module defines the class \class{NNTP} which implements the client