diff --git a/aws/resource_aws_network_acl_rule_test.go b/aws/resource_aws_network_acl_rule_test.go
index 1666705f11b0..67896693b18f 100644
--- a/aws/resource_aws_network_acl_rule_test.go
+++ b/aws/resource_aws_network_acl_rule_test.go
@@ -87,6 +87,39 @@ func TestAccAWSNetworkAclRule_ipv6ICMP(t *testing.T) {
 	})
 }
 
+// Reference: https://github.com/terraform-providers/terraform-provider-aws/issues/6710
+func TestAccAWSNetworkAclRule_ipv6VpcAssignGeneratedIpv6CidrBlockUpdate(t *testing.T) {
+	var networkAcl ec2.NetworkAcl
+	var vpc ec2.Vpc
+	vpcResourceName := "aws_vpc.test"
+	resourceName := "aws_network_acl_rule.test"
+
+	resource.ParallelTest(t, resource.TestCase{
+		PreCheck:     func() { testAccPreCheck(t) },
+		Providers:    testAccProviders,
+		CheckDestroy: testAccCheckAWSNetworkAclRuleDestroy,
+		Steps: []resource.TestStep{
+			{
+				Config: testAccAWSNetworkAclRuleConfigIpv6VpcAssignGeneratedIpv6CidrBlockUpdate(false),
+				Check: resource.ComposeTestCheckFunc(
+					testAccCheckVpcExists(vpcResourceName, &vpc),
+					resource.TestCheckResourceAttr(vpcResourceName, "assign_generated_ipv6_cidr_block", "false"),
+					resource.TestCheckResourceAttr(vpcResourceName, "ipv6_cidr_block", ""),
+				),
+			},
+			{
+				Config: testAccAWSNetworkAclRuleConfigIpv6VpcAssignGeneratedIpv6CidrBlockUpdate(true),
+				Check: resource.ComposeTestCheckFunc(
+					testAccCheckVpcExists(vpcResourceName, &vpc),
+					resource.TestCheckResourceAttr(vpcResourceName, "assign_generated_ipv6_cidr_block", "true"),
+					resource.TestMatchResourceAttr(vpcResourceName, "ipv6_cidr_block", regexp.MustCompile(`/56$`)),
+					testAccCheckAWSNetworkAclRuleExists(resourceName, &networkAcl),
+				),
+			},
+		},
+	})
+}
+
 func TestAccAWSNetworkAclRule_allProtocol(t *testing.T) {
 
 	resource.ParallelTest(t, resource.TestCase{
@@ -304,10 +337,6 @@ func testAccCheckAWSNetworkAclRuleDelete(n string) resource.TestCheckFunc {
 }
 
 const testAccAWSNetworkAclRuleBasicConfig = `
-provider "aws" {
-  region = "us-east-1"
-}
-
 resource "aws_vpc" "foo" {
 	cidr_block = "10.3.0.0/16"
 	tags = {
@@ -355,10 +384,6 @@ resource "aws_network_acl_rule" "wibble" {
 `
 
 const testAccAWSNetworkAclRuleMissingParam = `
-provider "aws" {
-  region = "us-east-1"
-}
-
 resource "aws_vpc" "foo" {
 	cidr_block = "10.3.0.0/16"
 	tags = {
@@ -540,3 +565,36 @@ resource "aws_network_acl_rule" "test" {
 }
 `, rName, rName)
 }
+
+func testAccAWSNetworkAclRuleConfigIpv6VpcAssignGeneratedIpv6CidrBlockUpdate(ipv6Enabled bool) string {
+	return fmt.Sprintf(`
+resource "aws_vpc" "test" {
+  assign_generated_ipv6_cidr_block = %[1]t
+  cidr_block                       = "10.3.0.0/16"
+
+  tags = {
+    Name = "tf-acc-test-network-acl-rule-ipv6-enabled"
+  }
+}
+
+resource "aws_network_acl" "test" {
+  vpc_id = "${aws_vpc.test.id}"
+
+  tags = {
+    Name = "tf-acc-test-network-acl-rule-ipv6-enabled"
+  }
+}
+
+resource "aws_network_acl_rule" "test" {
+  count = "${%[1]t ? 1 : 0}"
+
+  from_port       = 22
+  ipv6_cidr_block = "${aws_vpc.test.ipv6_cidr_block}"
+  network_acl_id  = "${aws_network_acl.test.id}"
+  protocol        = "tcp"
+  rule_action     = "allow"
+  rule_number     = 150
+  to_port         = 22
+}
+`, ipv6Enabled)
+}
diff --git a/aws/resource_aws_vpc.go b/aws/resource_aws_vpc.go
index 83f8b6da4184..5e07be0af68e 100644
--- a/aws/resource_aws_vpc.go
+++ b/aws/resource_aws_vpc.go
@@ -501,6 +501,14 @@ func resourceAwsVpcDelete(d *schema.ResourceData, meta interface{}) error {
 }
 
 func resourceAwsVpcCustomizeDiff(diff *schema.ResourceDiff, v interface{}) error {
+	if diff.HasChange("assign_generated_ipv6_cidr_block") {
+		if err := diff.SetNewComputed("ipv6_association_id"); err != nil {
+			return fmt.Errorf("error setting ipv6_association_id to computed: %s", err)
+		}
+		if err := diff.SetNewComputed("ipv6_cidr_block"); err != nil {
+			return fmt.Errorf("error setting ipv6_cidr_block to computed: %s", err)
+		}
+	}
 	if diff.HasChange("instance_tenancy") {
 		old, new := diff.GetChange("instance_tenancy")
 		if old.(string) != ec2.TenancyDedicated || new.(string) != ec2.TenancyDefault {