diff --git a/preseed/debian/buster/preseed.cfg b/preseed/debian/buster/preseed.cfg
index bfde9fa..3a9ffa3 100644
--- a/preseed/debian/buster/preseed.cfg
+++ b/preseed/debian/buster/preseed.cfg
@@ -293,6 +293,10 @@ d-i   apt-setup/non-free                          boolean     true
 d-i   apt-setup/contrib                           boolean     true
 d-i   apt-setup/enable-source-repositories        boolean     true
 
+## Ensure to use a network mirror
+### Set to false for an offline installation
+d-i   apt-setup/use_mirror                        boolean     true
+
 ## Choose packages
 tasksel tasksel/first                             multiselect ssh-server