diff --git a/lib/easy_translate.rb b/lib/easy_translate.rb
index be27d93..6657b19 100644
--- a/lib/easy_translate.rb
+++ b/lib/easy_translate.rb
@@ -16,6 +16,7 @@ module EasyTranslate
 
   class << self
     attr_accessor :api_key
+    attr_accessor :referer # for Google API key referer restriction
   end
 
 end
diff --git a/lib/easy_translate/request.rb b/lib/easy_translate/request.rb
index 7187b68..6fed7a3 100644
--- a/lib/easy_translate/request.rb
+++ b/lib/easy_translate/request.rb
@@ -37,11 +37,12 @@ def params
     # @return [String] The response String
     def perform_raw
       # Construct the request
-      request = Net::HTTP::Post.new(uri.request_uri)
-      request.add_field('X-HTTP-Method-Override', 'GET')
-      request.body = body
+      raw_request.add_field('Referer', EasyTranslate.referer)
+      raw_request.add_field('X-HTTP-Method-Override', 'GET')
+      raw_request.body = body
+
       # Fire and return
-      response = http.request(request)
+      response = http.request(raw_request)
       unless response.code == '200'
         err = JSON.parse(response.body)['error']['errors'].first['message']
         raise EasyTranslateException.new(err)
@@ -49,6 +50,10 @@ def perform_raw
       response.body
     end
 
+    def raw_request
+      @raw_request ||= Net::HTTP::Post.new(uri.request_uri)
+    end
+
     private
 
     def uri
diff --git a/spec/examples/request_spec.rb b/spec/examples/request_spec.rb
index 3c7fd44..d298fa6 100644
--- a/spec/examples/request_spec.rb
+++ b/spec/examples/request_spec.rb
@@ -2,6 +2,24 @@
 
 describe EasyTranslate::Request do
 
+  describe :perform_raw do
+    let(:referer) { 'https://example.com' }
+    let(:request) { EasyTranslate::Request.new }
+
+    before do
+      EasyTranslate.referer = referer
+
+      allow(request).to receive(:path).and_return('')
+    end
+
+    it 'should set headers' do
+      expect(request.raw_request).to receive(:add_field).once.ordered.with('Referer', EasyTranslate.referer)
+      expect(request.raw_request).to receive(:add_field).once.ordered.with('X-HTTP-Method-Override', 'GET')
+      expect { request.perform_raw }.to raise_error JSON::ParserError
+    end
+
+  end
+
   describe :path do
 
     it 'should raise a NotImplementedError on this base class' do