diff --git a/Doc/libstruct.tex b/Doc/libstruct.tex
index fa6919c..d0fde4f 100644
--- a/Doc/libstruct.tex
+++ b/Doc/libstruct.tex
@@ -1,7 +1,7 @@
 \section{Built-in Module \sectcode{struct}}
 \label{module-struct}
 \bimodindex{struct}
-\indexii{C}{structures}
+\indexii{C@\C{}}{structures}
 
 This module performs conversions between Python values and C
 structs represented as Python strings.  It uses \dfn{format strings}