diff --git a/debian/changelog b/debian/changelog
index 84fc082c..5b2dfccc 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -1,3 +1,11 @@
+livecd-rootfs (2.227) UNRELEASED; urgency=medium
+
+  * Pass --mirror-chroot-security and --mirror-binary-security in the
+    ubuntu-rtm case, as the default of http://security.ubuntu.com/ubuntu/
+    isn't going to have ubuntu-rtm suites.
+
+ -- Colin Watson <cjwatson@ubuntu.com>  Wed, 23 Jul 2014 10:59:21 +0100
+
 livecd-rootfs (2.226) utopic; urgency=medium
 
   * Disable apt authentication checks when building ubuntu-rtm images
diff --git a/live-build/auto/config b/live-build/auto/config
index a16529fb..d3aafda5 100755
--- a/live-build/auto/config
+++ b/live-build/auto/config
@@ -345,9 +345,13 @@ case $PROJECT in
 		    ubuntu-rtm/dogfood)
 			MIRROR=http://derived-archive.dogfood.content.paddev.net/ubuntu-rtm/
 			OPTS="${OPTS:+$OPTS }--apt-secure false"
+			OPTS="${OPTS:+$OPTS }--mirror-chroot-security ${MIRROR}"
+			OPTS="${OPTS:+$OPTS }--mirror-binary-security ${MIRROR}"
 			;;
 		    ubuntu-rtm)
 			MIRROR=http://derived.archive.canonical.com/ubuntu-rtm/
+			OPTS="${OPTS:+$OPTS }--mirror-chroot-security ${MIRROR}"
+			OPTS="${OPTS:+$OPTS }--mirror-binary-security ${MIRROR}"
 			;;
 		esac
 		;;