diff --git a/global/overlay/etc/puppet/cosmos-rules.yaml b/global/overlay/etc/puppet/cosmos-rules.yaml
index d9dc495..cffd808 100644
--- a/global/overlay/etc/puppet/cosmos-rules.yaml
+++ b/global/overlay/etc/puppet/cosmos-rules.yaml
@@ -1,2 +1,3 @@
-'ns[0-9]?.mnt.se$':
+# Note that the matching is done with re.match()
+'^ns[0-9]?.mnt.se$':
    nameserver: