diff --git a/builtin/providers/aws/resource_aws_db_instance.go b/builtin/providers/aws/resource_aws_db_instance.go
index 3ef3146ce..bfae70f8b 100644
--- a/builtin/providers/aws/resource_aws_db_instance.go
+++ b/builtin/providers/aws/resource_aws_db_instance.go
@@ -139,6 +139,13 @@ func resourceAwsDbInstance() *schema.Resource {
 				Type:     schema.TypeString,
 				Optional: true,
 				Computed: true,
+				StateFunc: func(v interface{}) string {
+					if v != nil {
+						value := v.(string)
+						return strings.ToLower(value)
+					}
+					return ""
+				},
 			},
 
 			"multi_az": &schema.Schema{
@@ -255,6 +262,12 @@ func resourceAwsDbInstance() *schema.Resource {
 				Optional: true,
 			},
 
+			"allow_major_version_upgrade": &schema.Schema{
+				Type:     schema.TypeBool,
+				Computed: false,
+				Optional: true,
+			},
+
 			"tags": tagsSchema(),
 		},
 	}
@@ -616,6 +629,11 @@ func resourceAwsDbInstanceUpdate(d *schema.ResourceData, meta interface{}) error
 		req.AllocatedStorage = aws.Int64(int64(d.Get("allocated_storage").(int)))
 		requestUpdate = true
 	}
+	if d.HasChange("allow_major_version_upgrade") {
+		d.SetPartial("allow_major_version_upgrade")
+		req.AllowMajorVersionUpgrade = aws.Bool(d.Get("allow_major_version_upgrade").(bool))
+		requestUpdate = true
+	}
 	if d.HasChange("backup_retention_period") {
 		d.SetPartial("backup_retention_period")
 		req.BackupRetentionPeriod = aws.Int64(int64(d.Get("backup_retention_period").(int)))
@@ -728,6 +746,7 @@ func resourceAwsDbInstanceUpdate(d *schema.ResourceData, meta interface{}) error
 		}
 	}
 	d.Partial(false)
+
 	return resourceAwsDbInstanceRead(d, meta)
 }
 
@@ -742,7 +761,6 @@ func resourceAwsDbInstanceRetrieve(
 	log.Printf("[DEBUG] DB Instance describe configuration: %#v", opts)
 
 	resp, err := conn.DescribeDBInstances(&opts)
-
 	if err != nil {
 		dbinstanceerr, ok := err.(awserr.Error)
 		if ok && dbinstanceerr.Code() == "DBInstanceNotFound" {
diff --git a/builtin/providers/aws/resource_aws_db_instance_test.go b/builtin/providers/aws/resource_aws_db_instance_test.go
index b60a01da9..e63be73a8 100644
--- a/builtin/providers/aws/resource_aws_db_instance_test.go
+++ b/builtin/providers/aws/resource_aws_db_instance_test.go
@@ -183,6 +183,12 @@ resource "aws_db_instance" "bar" {
 	password = "barbarbarbar"
 	username = "foo"
 
+
+	# Maintenance Window is stored in lower case in the API, though not strictly 
+	# documented. Terraform will downcase this to match (as opposed to throw a 
+	# validation error).
+	maintenance_window = "Fri:09:00-Fri:09:30"
+
 	backup_retention_period = 0
 
 	parameter_group_name = "default.mysql5.6"
diff --git a/builtin/providers/aws/resource_aws_db_subnet_group.go b/builtin/providers/aws/resource_aws_db_subnet_group.go
index 3d8ebc833..9c09b72d7 100644
--- a/builtin/providers/aws/resource_aws_db_subnet_group.go
+++ b/builtin/providers/aws/resource_aws_db_subnet_group.go
@@ -18,6 +18,7 @@ func resourceAwsDbSubnetGroup() *schema.Resource {
 	return &schema.Resource{
 		Create: resourceAwsDbSubnetGroupCreate,
 		Read:   resourceAwsDbSubnetGroupRead,
+		Update: resourceAwsDbSubnetGroupUpdate,
 		Delete: resourceAwsDbSubnetGroupDelete,
 
 		Schema: map[string]*schema.Schema{
@@ -52,7 +53,6 @@ func resourceAwsDbSubnetGroup() *schema.Resource {
 			"subnet_ids": &schema.Schema{
 				Type:     schema.TypeSet,
 				Required: true,
-				ForceNew: true,
 				Elem:     &schema.Schema{Type: schema.TypeString},
 				Set:      schema.HashString,
 			},
@@ -133,6 +133,32 @@ func resourceAwsDbSubnetGroupRead(d *schema.ResourceData, meta interface{}) erro
 	return nil
 }
 
+func resourceAwsDbSubnetGroupUpdate(d *schema.ResourceData, meta interface{}) error {
+	conn := meta.(*AWSClient).rdsconn
+	if d.HasChange("subnet_ids") {
+		_, n := d.GetChange("subnet_ids")
+		if n == nil {
+			n = new(schema.Set)
+		}
+		ns := n.(*schema.Set)
+
+		var sIds []*string
+		for _, s := range ns.List() {
+			sIds = append(sIds, aws.String(s.(string)))
+		}
+
+		_, err := conn.ModifyDBSubnetGroup(&rds.ModifyDBSubnetGroupInput{
+			DBSubnetGroupName: aws.String(d.Id()),
+			SubnetIds:         sIds,
+		})
+
+		if err != nil {
+			return err
+		}
+	}
+	return resourceAwsDbSubnetGroupRead(d, meta)
+}
+
 func resourceAwsDbSubnetGroupDelete(d *schema.ResourceData, meta interface{}) error {
 	stateConf := &resource.StateChangeConf{
 		Pending:    []string{"pending"},