diff --git a/lib/fog/aws/requests/compute/run_instances.rb b/lib/fog/aws/requests/compute/run_instances.rb
index aac4dcf5c..5f55a021a 100644
--- a/lib/fog/aws/requests/compute/run_instances.rb
+++ b/lib/fog/aws/requests/compute/run_instances.rb
@@ -28,6 +28,8 @@ module Fog
         #     * 'Ebs.SnapshotId'<~String> - id of snapshot to boot volume from
         #     * 'Ebs.VolumeSize'<~String> - size of volume in GiBs required unless snapshot is specified
         #     * 'Ebs.DeleteOnTermination'<~String> - specifies whether or not to delete the volume on instance termination
+        #     * 'Ebs.VolumeType'<~String> - Type of EBS volue. Valid options in ['standard', 'io1'] default is 'standard'.
+        #     * 'Ebs.Iops'<~String> - The number of I/O operations per second (IOPS) that the volume supports. Required when VolumeType is 'io1'
         #   * 'ClientToken'<~String> - unique case-sensitive token for ensuring idempotency
         #   * 'DisableApiTermination'<~Boolean> - specifies whether or not to allow termination of the instance from the api
         #   * 'SecurityGroup'<~Array> or <~String> - Name of security group(s) for instances (not supported for VPC)