diff --git a/traefik/base/003-certificates.yaml b/traefik/base/003-certificates.yaml
index da0be83..0a92fa2 100644
--- a/traefik/base/003-certificates.yaml
+++ b/traefik/base/003-certificates.yaml
@@ -9,8 +9,8 @@ spec:
     name: cloudflare-issuer
     kind: ClusterIssuer
   dnsNames:
-    - mziesel.nl
-    - *.mziesel.nl
+    - 'mziesel.nl'
+    - '*.mziesel.nl'
 ---
 apiVersion: cert-manager.io/v1
 kind: Certificate
@@ -22,8 +22,8 @@ spec:
     name: cloudflare-issuer
     kind: ClusterIssuer
   dnsNames:
-    - mziesel.com
-    - *.mziesel.com
+    - 'mziesel.com'
+    - '*.mziesel.com'
 ---
 apiVersion: traefik.io/v1alpha1
 kind: TLSStore