diff --git a/ubuntu-14.04/http/preseed-lvm.cfg b/ubuntu-14.04/http/preseed-lvm.cfg
index 528a577..690b7d0 100644
--- a/ubuntu-14.04/http/preseed-lvm.cfg
+++ b/ubuntu-14.04/http/preseed-lvm.cfg
@@ -1,6 +1,7 @@
 d-i apt-setup/use_mirror boolean false
 d-i apt-setup/local0/repository string [arch=amd64] http://apt.cloudlab.cz/nightly trusty main cloudlab security
 d-i apt-setup/local0/key string http://apt.cloudlab.cz/public.gpg
+d-i preseed/late_command string sed -i '/.*security\.ubuntu.com.*/d' /etc/apt/sources.list
 
 d-i debian-installer/framebuffer boolean false
 d-i debconf/frontend select noninteractive
diff --git a/ubuntu-14.04/http/preseed.cfg b/ubuntu-14.04/http/preseed.cfg
index adb5924..4a82241 100644
--- a/ubuntu-14.04/http/preseed.cfg
+++ b/ubuntu-14.04/http/preseed.cfg
@@ -1,6 +1,7 @@
 d-i apt-setup/use_mirror boolean false
 d-i apt-setup/local0/repository string [arch=amd64] http://apt.cloudlab.cz/nightly trusty main cloudlab security
 d-i apt-setup/local0/key string http://apt.cloudlab.cz/public.gpg
+d-i preseed/late_command string sed -i '/.*security\.ubuntu.com.*/d' /etc/apt/sources.list
 
 d-i debian-installer/framebuffer boolean false
 d-i debconf/frontend select noninteractive