diff --git a/software/zimbra/BACKUP.txt b/software/zimbra/BACKUP.txt
index d7d8ee4344323a5370410b65f965ef05ef0399a7..fc4ec9a7d382df8dfda1307727d9e869d8606bcc 100644
--- a/software/zimbra/BACKUP.txt
+++ b/software/zimbra/BACKUP.txt
@@ -244,6 +244,8 @@ is described in
 
     http://blog.spanger.org/?p=1168
 
+but it also requires to install the old version on the new server.
+
 
 
 Version upgrade: Buildout Edition
@@ -288,3 +290,4 @@ The procedure described in
 
 could also be adapted to the Buildout Edition.
 
+