diff --git a/main.tf b/main.tf
index e117edc..64e36f6 100644
--- a/main.tf
+++ b/main.tf
@@ -10,7 +10,7 @@ resource "aws_acm_certificate" "this" {
   count = var.create_certificate ? 1 : 0
 
   domain_name               = var.domain_name
-  subject_alternative_names = var.subject_alternative_names
+  subject_alternative_names = sort(var.subject_alternative_names)
   validation_method         = var.validation_method
 
   options {