diff --git a/lib/fog/aws/elasticache.rb b/lib/fog/aws/elasticache.rb
index 5079d9826..dcb7a3ffb 100644
--- a/lib/fog/aws/elasticache.rb
+++ b/lib/fog/aws/elasticache.rb
@@ -3,6 +3,7 @@ module Fog
     class Elasticache < Fog::Service
 
       class IdentifierTaken < Fog::Errors::Error; end
+      class InvalidInstance < Fog::Errors::Error; end
 
       requires :aws_access_key_id, :aws_secret_access_key
       recognizes :region, :host, :path, :port, :scheme, :persistent