diff --git a/lib/fog/aws/models/rds/server.rb b/lib/fog/aws/models/rds/server.rb
index e0d22a8de..890722cfe 100644
--- a/lib/fog/aws/models/rds/server.rb
+++ b/lib/fog/aws/models/rds/server.rb
@@ -87,9 +87,14 @@ module Fog
 
         def promote_read_replica
           requires :id
-          service.promote_read_replica(id)
+
+          data = service.promote_read_replica(id).body["PromoteReadReplicaResult"]["DBInstance"]
+
+          merge_attributes(data)
         end
 
+        alias promote promote_read_replica
+
         def modify(immediately, options)
           options[:security_group_names] ||= options['DBSecurityGroups']
           params = self.class.new(options).attributes_to_params
diff --git a/lib/fog/aws/requests/rds/describe_db_instances.rb b/lib/fog/aws/requests/rds/describe_db_instances.rb
index 2bc663e5d..1ad8d5be4 100644
--- a/lib/fog/aws/requests/rds/describe_db_instances.rb
+++ b/lib/fog/aws/requests/rds/describe_db_instances.rb
@@ -77,7 +77,7 @@ module Fog
 
           response.status = 200
           response.body = {
-            "ResponseMetadata"=>{ "RequestId"=> Fog::AWS::Mock.request_id },
+            "ResponseMetadata"          => { "RequestId"   => Fog::AWS::Mock.request_id },
             "DescribeDBInstancesResult" => { "DBInstances" => server_set }
           }
           response
diff --git a/lib/fog/aws/requests/rds/describe_db_snapshots.rb b/lib/fog/aws/requests/rds/describe_db_snapshots.rb
index 1ab314d9e..8988cc33a 100644
--- a/lib/fog/aws/requests/rds/describe_db_snapshots.rb
+++ b/lib/fog/aws/requests/rds/describe_db_snapshots.rb
@@ -35,11 +35,12 @@ module Fog
           response = Excon::Response.new
           snapshots = self.data[:snapshots].values
           if opts[:identifier]
-            snapshots = snapshots.select{|snapshot| snapshot['DBInstanceIdentifier'] == opts[:identifier]}
+            snapshots = snapshots.select { |snapshot| snapshot['DBInstanceIdentifier'] == opts[:identifier] }
+
           end
 
           if opts[:snapshot_id]
-            snapshots = snapshots.select{|snapshot| snapshot['DBSnapshotIdentifier'] == opts[:snapshot_id]}
+            snapshots = snapshots.select { |snapshot| snapshot['DBSnapshotIdentifier'] == opts[:snapshot_id] }
             raise Fog::AWS::RDS::NotFound.new("DBSnapshot #{opts[:snapshot_id]} not found") if snapshots.empty?
           end
 
diff --git a/lib/fog/aws/requests/rds/promote_read_replica.rb b/lib/fog/aws/requests/rds/promote_read_replica.rb
index a398b0628..76f083118 100644
--- a/lib/fog/aws/requests/rds/promote_read_replica.rb
+++ b/lib/fog/aws/requests/rds/promote_read_replica.rb
@@ -25,34 +25,43 @@ module Fog
           params['BackupRetentionPeriod'] = backup_retention_period if backup_retention_period
           params['PreferredBackupWindow'] = preferred_backup_window if preferred_backup_window
           request({
-            'Action'  => 'PromoteReadReplica',
+            'Action'               => 'PromoteReadReplica',
             'DBInstanceIdentifier' => identifier,
-            :parser   => Fog::Parsers::AWS::RDS::PromoteReadReplica.new
+            :parser                => Fog::Parsers::AWS::RDS::PromoteReadReplica.new
           }.merge(params))
         end
       end
 
       class Mock
         def promote_read_replica(identifier, backup_retention_period = nil, preferred_backup_window = nil)
-          if self.data[:servers][identifier]
-            data = {
-              'BackupRetentionPeriod' => backup_retention_period || 1,
-              'PreferredBackupWindow' => preferred_backup_window || '08:00-08:30',
-              'DBInstanceIdentifier' => identifier,
-            }
+          server = self.data[:servers][identifier]
+          server || raise(Fog::AWS::RDS::NotFound.new("DBInstance #{identifier} not found"))
 
-            db_instance = self.data[:servers][identifier].merge(data)
-
-            response = Excon::Response.new
-            response.body = {
-              "ResponseMetadata"         => { "RequestId"  => Fog::AWS::Mock.request_id },
-              "PromoteReadReplicaResult" => { "DBInstance" => db_instance }
-            }
-            response.status = 200
-            response
-          else
-            raise Fog::AWS::RDS::NotFound.new("DBInstance #{identifier} not found")
+          if server["ReadReplicaSourceDBInstanceIdentifier"].nil?
+            raise(Fog::AWS::RDS::Error.new("InvalidDBInstanceState => DB Instance is not a read replica."))
           end
+
+          self.data[:modify_time] = Time.now
+
+          data = {
+            'BackupRetentionPeriod' => backup_retention_period || 1,
+            'PreferredBackupWindow' => preferred_backup_window || '08:00-08:30',
+            'DBInstanceIdentifier'  => identifier,
+            'DBInstanceStatus'      => "modifying",
+            'PendingModifiedValues' => {
+              'ReadReplicaSourceDBInstanceIdentifier' => nil,
+            }
+          }
+
+          server.merge!(data)
+
+          response = Excon::Response.new
+          response.body = {
+            "ResponseMetadata"         => { "RequestId"  => Fog::AWS::Mock.request_id },
+            "PromoteReadReplicaResult" => { "DBInstance" => server }
+          }
+          response.status = 200
+          response
         end
       end
     end
diff --git a/tests/models/rds/server_tests.rb b/tests/models/rds/server_tests.rb
index 2005e3b93..0da179cc6 100644
--- a/tests/models/rds/server_tests.rb
+++ b/tests/models/rds/server_tests.rb
@@ -87,8 +87,9 @@ Shindo.tests("AWS::RDS | server", ['aws', 'rds']) do
     @instance.wait_for { state == 'rebooting' }
     @instance.wait_for { ready? }
 
-    tests('#create_read_replica').succeeds do
+    replica = nil
 
+    tests('#create_read_replica').succeeds do
       replica = @instance_with_final_snapshot.create_read_replica(uniq_id('fog-replica'))
       @instance_with_final_snapshot.reload
       returns([replica.id]) { @instance_with_final_snapshot.read_replica_identifiers }
@@ -98,10 +99,20 @@ Shindo.tests("AWS::RDS | server", ['aws', 'rds']) do
 
       # FinalDBSnapshotIdentifier can not be specified when deleting a replica instance
       raises(Fog::AWS::RDS::Error) { replica.destroy("foobar") }
-
-      replica.destroy
     end
 
+    tests('#promote_read_replica').succeeds do
+      replica.promote.wait_for { state != "modifying" }
+
+      replica.read_replica_source == nil
+    end
+
+    tests('#promote_read_replica', 'master').raises(Fog::AWS::RDS::Error) {
+      @instance_with_final_snapshot.promote
+    }
+
+    replica && replica.destroy
+
     test("Destroying with a final snapshot") do
       final_snapshot_id = uniq_id('fog-test-snapshot')