diff --git a/api/dns-defs.yaml b/api/dns-defs.yaml
index 8ed2da19..2b3bc33d 100644
--- a/api/dns-defs.yaml
+++ b/api/dns-defs.yaml
@@ -59,6 +59,7 @@
         format: date-time
       serial:
         type: integer
+        x-omitempty: false
       view:
         type: string
       zoneType: