diff --git a/README.md b/README.md
index 00e529cf..7cbfd151 100644
--- a/README.md
+++ b/README.md
@@ -29,7 +29,7 @@ $ gem install minfraud
 
 ## Configuration
 
-User Id and License Key are required to work with minFraud API
+Account ID and License Key are required to work with minFraud API
 
 ```ruby
 Minfraud.configure do |c|
@@ -86,7 +86,7 @@ class RequestFormatError < BaseError; end
 # Raised if IP address is absent / it is reserved / JSON body can not be decoded
 class ClientError < BaseError; end
 
-# Raised if there are some problems with the user id and / or license key
+# Raised if there are some problems with the account ID and / or license key
 class AuthorizationError < BaseError; end
 
 # Raised if minFraud returns an error, or if there is an HTTP error
diff --git a/lib/minfraud.rb b/lib/minfraud.rb
index 5674524e..9d1faf2d 100644
--- a/lib/minfraud.rb
+++ b/lib/minfraud.rb
@@ -27,7 +27,7 @@
 module Minfraud
   class << self
     # @!attribute user_id
-    # @return [String] MaxMind username that is used for authorization
+    # @return [String] MaxMind account ID that is used for authorization
     attr_accessor :user_id
 
     # @!attribute license_key
diff --git a/lib/minfraud/error_handler.rb b/lib/minfraud/error_handler.rb
index 27ce1b92..abf6c893 100644
--- a/lib/minfraud/error_handler.rb
+++ b/lib/minfraud/error_handler.rb
@@ -24,14 +24,17 @@ def inspect(response)
         JSON_INVALID:          [
           ClientError, 'JSON body cannot be decoded'
         ],
+        ACCOUNT_ID_REQUIRED:      [
+          AuthorizationError, 'You have not supplied a account ID'
+        ],
         AUTHORIZATION_INVALID: [
-          AuthorizationError, 'Invalid license key and / or user id'
+          AuthorizationError, 'Invalid license key and / or account ID'
         ],
         LICENSE_KEY_REQUIRED:  [
           AuthorizationError, 'You have not supplied a license key'
         ],
         USER_ID_REQUIRED:      [
-          AuthorizationError, 'You have not supplied a user id'
+          AuthorizationError, 'You have not supplied a account id'
         ],
         INSUFFICIENT_FUNDS:    [
           ClientError, 'The license key you have provided does not have a sufficient funds to use this service'