diff --git a/elements/ubuntu/README.md b/elements/ubuntu/README.md
index 009afe93..9fc02df8 100644
--- a/elements/ubuntu/README.md
+++ b/elements/ubuntu/README.md
@@ -6,5 +6,5 @@ Overrides:
    use the environment variable DIB\_CLOUD\_IMAGES
  * To download a non-default release of Ubuntu cloud images, use the
    environment variable DIB\_RELEASE
- * To use a different mirror rather than archive.ubuntu.com, use the
-   environment variable DIB\_DISTRIBUTION\_MIRROR
+ * To use different mirrors rather than the default of archive.ubuntu.com and
+   security.ubuntu.com, use the environment variable DIB\_DISTRIBUTION\_MIRROR
diff --git a/elements/ubuntu/pre-install.d/01-set-ubuntu-mirror b/elements/ubuntu/pre-install.d/01-set-ubuntu-mirror
index 9633e9cd..a1b36494 100755
--- a/elements/ubuntu/pre-install.d/01-set-ubuntu-mirror
+++ b/elements/ubuntu/pre-install.d/01-set-ubuntu-mirror
@@ -6,5 +6,5 @@ DIB_DISTRIBUTION_MIRROR=${DIB_DISTRIBUTION_MIRROR:-}
 
 [ -n "$DIB_DISTRIBUTION_MIRROR" ] || exit 0
 
-sudo sed -ie "s&http://archive.ubuntu.com/ubuntu&$DIB_DISTRIBUTION_MIRROR&" \
+sudo sed -ie "s&http://\(archive\|security\).ubuntu.com/ubuntu&$DIB_DISTRIBUTION_MIRROR&" \
     /etc/apt/sources.list