diff --git a/lib/differential.rb b/lib/differential.rb
index a0a4993..e794b6c 100644
--- a/lib/differential.rb
+++ b/lib/differential.rb
@@ -1,33 +1,35 @@
 # frozen_string_literal: true
 #
 # Copyright (C) 2016 Harald Sitter <sitter@kde.org>
 #
 # This library is free software; you can redistribute it and/or
 # modify it under the terms of the GNU Lesser General Public
 # License as published by the Free Software Foundation; either
 # version 2.1 of the License, or (at your option) version 3, or any
 # later version accepted by the membership of KDE e.V. (or its
 # successor approved by the membership of KDE e.V.), which shall
 # act as a proxy defined in Section 6 of version 3 of the license.
 #
 # This library is distributed in the hope that it will be useful,
 # but WITHOUT ANY WARRANTY; without even the implied warranty of
 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 # Lesser General Public License for more details.
 #
 # You should have received a copy of the GNU Lesser General Public
 # License along with this library.  If not, see <http://www.gnu.org/licenses/>.
 
 require(File.expand_path('connection', File.dirname(__FILE__)))
 require(File.expand_path('representation', File.dirname(__FILE__)))
 
 module Conduit
   # A code review
   class Differential < Representation
     class << self
       def get(id, connection = Connection.new)
-        new(connection, connection.call('differential.query', ids: [id])[0])
+        data = connection.call('differential.query', ids: [id])
+        raise 'Empty response from Phabricator' if !data || data.empty?
+        new(connection, data[0])
       end
     end
   end
 end
diff --git a/test/plugin_test.rb b/test/plugin_test.rb
index dab8fe7..e7cde56 100644
--- a/test/plugin_test.rb
+++ b/test/plugin_test.rb
@@ -1,124 +1,124 @@
 # encoding: utf-8
 
 require(File.expand_path('test_helper', File.dirname(__FILE__)))
 
 # Dud base class. We mocha this for functionality later.
 class Plugin
   class Config
     class StringValue
       def initialize(_, _ = {})
       end
     end
     def self.register(_)
     end
   end
 
   def map(*args)
   end
 
   def bot
   end
 end
 
 require 'phabricator'
 
 class PluginTest < Test::Unit::TestCase
 
   # NB: mocha is stupid with the quotes and can't tell single from double!
 
   def setup
     config = mock('config')
     # Do not give an api_token as we need the environment to take over.
     config.stubs(:[]).with('phabricator.api_token').returns(nil)
     bot = mock('bot')
     bot.stubs(:config).returns(config)
     Plugin.any_instance.stubs(:bot).returns(bot)
   end
 
   def message_double
     channel = mock('message-channel')
     channel.stubs(:name).returns('#message-double-channel')
     mock('message').tap { |m| m.stubs(:channel).returns(channel) }
   end
 
   def test_get_task_unreplied
     message = message_double
     message.stubs(:message).returns('yolo T123 T456 meow T789')
     message.stubs(:replied?).returns(false)
 
     plugin = PhabricatorPlugin.new
     plugin.expects(:task).with(message, { :number => '123' })
     plugin.expects(:task).with(message, { :number => '456' })
     plugin.expects(:task).with(message, { :number => '789' })
     plugin.unreplied(message)
   end
 
   def test_get_diff_unreplied
     message = message_double
     message.stubs(:message).returns('yolo D123 D456 meow D789')
     message.stubs(:replied?).returns(false)
 
     plugin = PhabricatorPlugin.new
     plugin.expects(:diff).with(message, { :number => '123' })
     plugin.expects(:diff).with(message, { :number => '456' })
     plugin.expects(:diff).with(message, { :number => '789' })
     plugin.unreplied(message)
   end
 
   def test_task
     message = message_double
     message.expects(:reply).with('Task 2970 "aptly sftp publishing to files.kde" [Open,Normal] {Neon} https://phabricator.kde.org/T2970')
 
     VCR.use_cassette("#{self.class}/#{__method__}") do
       plugin = PhabricatorPlugin.new
       plugin.task(message, :number => 2970)
     end
   end
 
   def test_task_fail
     message = message_double
     message.expects(:notify).with('Task not found ¯\_(ツ)_/¯ ConduitError ERR_BAD_TASK: No such Maniphest task exists.')
 
     VCR.use_cassette(__method__) do
       plugin = PhabricatorPlugin.new
       plugin.task(message, :number => -1)
     end
   end
 
   def test_diff
     message = message_double
     message.expects(:reply).with('Diff 2300 "always load about-distro in ctor" [Closed] https://phabricator.kde.org/D2300')
 
     VCR.use_cassette("#{self.class}/#{__method__}") do
       plugin = PhabricatorPlugin.new
       plugin.diff(message, :number => 2300)
     end
   end
 
   def test_diff_fail
     message = message_double
-    message.expects(:notify).with('Diff not found ¯\_(ツ)_/¯ can\'t dup NilClass')
+    message.expects(:notify).with('Diff not found ¯\_(ツ)_/¯ Empty response from Phabricator')
 
     VCR.use_cassette(__method__) do
       plugin = PhabricatorPlugin.new
       plugin.diff(message, :number => -1)
     end
   end
 
   def test_skip
     message = message_double
     message.channel.stubs(:name).returns('#kde-bugs-activity')
     plugin = PhabricatorPlugin.new
     plugin.unreplied(message)
   end
 
   def test_task_with_no_projects
     message = message_double
     message.expects(:reply).with('Task 8149 "Rewritten Dragon player UI in Kirigami (QML)" [Open,Wishlist] {} https://phabricator.kde.org/T8149')
 
     VCR.use_cassette("#{self.class}/#{__method__}") do
       plugin = PhabricatorPlugin.new
       plugin.task(message, :number => 8149)
     end
   end
 end