diff --git a/docs/resources/tls_mutual_authentication.md b/docs/resources/tls_mutual_authentication.md
index 45eac7f6a..8e9b6acc8 100644
--- a/docs/resources/tls_mutual_authentication.md
+++ b/docs/resources/tls_mutual_authentication.md
@@ -66,7 +66,7 @@ resource "fastly_service_vcl" "example" {
 
 resource "fastly_tls_subscription" "www" {
   domains               = [for domain in fastly_service_vcl.example.domain : domain.name if domain.name == "www.${var.zone}"]
-  certificate_authority = "lets-encrypt"
+  certificate_authority = "certainly"
 }
 
 resource "dnsimple_zone_record" "www_acme_challenge" {
@@ -160,7 +160,7 @@ resource "fastly_service_vcl" "example" {
 
 resource "fastly_tls_subscription" "example" {
   domains               = [for domain in fastly_service_vcl.example.domain : domain.name]
-  certificate_authority = "lets-encrypt"
+  certificate_authority = "certainly"
 }
 
 resource "dnsimple_zone_record" "example_acme_challenge" {
diff --git a/examples/resources/tls_mutual_authentication_basic_usage.tf b/examples/resources/tls_mutual_authentication_basic_usage.tf
index 5cd874dcb..7ac89e36a 100644
--- a/examples/resources/tls_mutual_authentication_basic_usage.tf
+++ b/examples/resources/tls_mutual_authentication_basic_usage.tf
@@ -43,7 +43,7 @@ resource "fastly_service_vcl" "example" {
 
 resource "fastly_tls_subscription" "www" {
   domains               = [for domain in fastly_service_vcl.example.domain : domain.name if domain.name == "www.${var.zone}"]
-  certificate_authority = "lets-encrypt"
+  certificate_authority = "certainly"
 }
 
 resource "dnsimple_zone_record" "www_acme_challenge" {
diff --git a/examples/resources/tls_mutual_authentication_multiple_activations.tf b/examples/resources/tls_mutual_authentication_multiple_activations.tf
index 1cd921925..65eac3dec 100644
--- a/examples/resources/tls_mutual_authentication_multiple_activations.tf
+++ b/examples/resources/tls_mutual_authentication_multiple_activations.tf
@@ -46,7 +46,7 @@ resource "fastly_service_vcl" "example" {
 
 resource "fastly_tls_subscription" "example" {
   domains               = [for domain in fastly_service_vcl.example.domain : domain.name]
-  certificate_authority = "lets-encrypt"
+  certificate_authority = "certainly"
 }
 
 resource "dnsimple_zone_record" "example_acme_challenge" {