diff --git a/templates/lxc-debian.in b/templates/lxc-debian.in
index d9f0f03cb..39146054c 100644
--- a/templates/lxc-debian.in
+++ b/templates/lxc-debian.in
@@ -161,8 +161,13 @@ write_sourceslist()
 
     cat >> "${rootfs}/etc/apt/sources.list" << EOF
 ${prefix} $MIRROR          ${release}         main contrib non-free
+EOF
+
+    if [ "$release" != "unstable" -a "$release" != "sid" ]; then
+      cat >> "${rootfs}/etc/apt/sources.list" << EOF
 ${prefix} $SECURITY_MIRROR ${release}/updates main contrib non-free
 EOF
+    fi
 }
 
 install_packages()