diff --git a/doc/user_guide/wannier90.tex b/doc/user_guide/wannier90.tex
index f895a17c3..138ea4b40 100644
--- a/doc/user_guide/wannier90.tex
+++ b/doc/user_guide/wannier90.tex
@@ -42,7 +42,7 @@ \chapter{Methodology}\label{sec:method}
 where
 \begin{equation}
 \Omega_{{\rm I}}=\sum_n \left[\langle w_{n{\bf 0}}({\bf r})| r^2 | w_{n{\bf
-      0}}({\bf r}) \rangle - \sum_{{\bf R}m} \left| \langle w_{n{\bf
+      0}}({\bf r}) \rangle - \sum_{{\bf R}m} \left| \langle w_{m{\bf
       R}}({\bf r})| {\bf r} | w_{n{\bf 0}}({\bf r}) \rangle \right| ^2
       \right] 
 \end{equation}