diff --git a/main.tf b/main.tf
index 0e5204b..d4d2a1e 100644
--- a/main.tf
+++ b/main.tf
@@ -51,8 +51,8 @@ locals {
     local.tags_email,
     local.tags_reference[var.reference != "" ? "exists" : "not_exists"]
   )
-  aws_access_key_id     = concat(aws_iam_access_key.audit[*].id, list(""))
-  aws_secret_access_key = concat(aws_iam_access_key.audit[*].encrypted_secret, list(""))
+  aws_access_key_id     = concat(aws_iam_access_key.audit[*].id, tolist(""))
+  aws_secret_access_key = concat(aws_iam_access_key.audit[*].encrypted_secret, tolist(""))
 
   policies = compact(concat([data.aws_iam_policy.aws-managed-security-audit.arn], var.additional_policies))
 }