diff --git a/backend/models/certificate.js b/backend/models/certificate.js
index 8ca859cd..954255b9 100644
--- a/backend/models/certificate.js
+++ b/backend/models/certificate.js
@@ -38,6 +38,8 @@ class Certificate extends Model {
 		// Default for domain_names
 		if (typeof this.domain_names !== "undefined") {
 			this.domain_names = cleanDomainNames(this.domain_names);
+		} else {
+			this.domain_names = [];
 		}
 
 		// Default for meta