diff --git a/readme.txt b/readme.txt
index 8adfd87..5bf72d3 100644
--- a/readme.txt
+++ b/readme.txt
@@ -1,6 +1,6 @@
 Need to install some perl module :
 
-yum -y install perl-JSON perl-Statistics-Descriptive
+yum -y install perl-JSON perl-Statistics-Descriptive perl-IPC-System-Simple
 
 Update script :
 cd BackupPC-Check