diff --git a/CHANGELOG.md b/CHANGELOG.md
index e39ce1d..d67b514 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,7 @@
+# 1.7.0
+
+  * [ENHANCEMENT] support frozen string literals (also: avoid RuntimeError in Rack::Tracker#inject #114 thx @zpfled)
+
 # 1.6.0
 
   * [BUGFIX] set wildcard to non-greedy for GTM body insertion #107
diff --git a/Rakefile b/Rakefile
index c382fee..c38f0b1 100644
--- a/Rakefile
+++ b/Rakefile
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require "bundler/gem_tasks"
 require 'rspec/core/rake_task'
 
diff --git a/lib/rack/tracker.rb b/lib/rack/tracker.rb
index f2141f0..5b8a947 100644
--- a/lib/rack/tracker.rb
+++ b/lib/rack/tracker.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require "rack"
 require "tilt"
 require "active_support/core_ext/class/attribute"
diff --git a/lib/rack/tracker/controller.rb b/lib/rack/tracker/controller.rb
index 801a52a..79464fc 100644
--- a/lib/rack/tracker/controller.rb
+++ b/lib/rack/tracker/controller.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Rack
   class Tracker
     module Controller
diff --git a/lib/rack/tracker/criteo/criteo.rb b/lib/rack/tracker/criteo/criteo.rb
index 5a71c7b..91736cb 100644
--- a/lib/rack/tracker/criteo/criteo.rb
+++ b/lib/rack/tracker/criteo/criteo.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Rack::Tracker::Criteo < Rack::Tracker::Handler
 
   TRACKER_EVENTS = {
diff --git a/lib/rack/tracker/extensions.rb b/lib/rack/tracker/extensions.rb
index bfbe832..951def0 100644
--- a/lib/rack/tracker/extensions.rb
+++ b/lib/rack/tracker/extensions.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'ostruct'
 
 # Backport of 2.0.0 stdlib ostruct#to_h
diff --git a/lib/rack/tracker/facebook/facebook.rb b/lib/rack/tracker/facebook/facebook.rb
index 67a9311..8b59749 100644
--- a/lib/rack/tracker/facebook/facebook.rb
+++ b/lib/rack/tracker/facebook/facebook.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Rack::Tracker::Facebook < Rack::Tracker::Handler
   class Event < OpenStruct
     def write
diff --git a/lib/rack/tracker/facebook_pixel/facebook_pixel.rb b/lib/rack/tracker/facebook_pixel/facebook_pixel.rb
index f6015dd..b182c86 100644
--- a/lib/rack/tracker/facebook_pixel/facebook_pixel.rb
+++ b/lib/rack/tracker/facebook_pixel/facebook_pixel.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Rack::Tracker::FacebookPixel < Rack::Tracker::Handler
   self.position = :body
   self.allowed_tracker_options = [:id]
diff --git a/lib/rack/tracker/go_squared/go_squared.rb b/lib/rack/tracker/go_squared/go_squared.rb
index 7885d0a..8ea87df 100644
--- a/lib/rack/tracker/go_squared/go_squared.rb
+++ b/lib/rack/tracker/go_squared/go_squared.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Rack::Tracker::GoSquared < Rack::Tracker::Handler
   class VisitorName < OpenStruct
     def write
diff --git a/lib/rack/tracker/google_adwords_conversion/google_adwords_conversion.rb b/lib/rack/tracker/google_adwords_conversion/google_adwords_conversion.rb
index ecdf652..f765ffc 100644
--- a/lib/rack/tracker/google_adwords_conversion/google_adwords_conversion.rb
+++ b/lib/rack/tracker/google_adwords_conversion/google_adwords_conversion.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Rack::Tracker::GoogleAdwordsConversion < Rack::Tracker::Handler
   class Conversion < OpenStruct
   end
diff --git a/lib/rack/tracker/google_analytics/google_analytics.rb b/lib/rack/tracker/google_analytics/google_analytics.rb
index a359cc1..3fbfc9a 100644
--- a/lib/rack/tracker/google_analytics/google_analytics.rb
+++ b/lib/rack/tracker/google_analytics/google_analytics.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Rack::Tracker::GoogleAnalytics < Rack::Tracker::Handler
 
   self.allowed_tracker_options = [:cookie_domain, :user_id]
diff --git a/lib/rack/tracker/google_tag_manager/google_tag_manager.rb b/lib/rack/tracker/google_tag_manager/google_tag_manager.rb
index 2db9d2b..8784301 100644
--- a/lib/rack/tracker/google_tag_manager/google_tag_manager.rb
+++ b/lib/rack/tracker/google_tag_manager/google_tag_manager.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Rack::Tracker::GoogleTagManager < Rack::Tracker::Handler
 
   class Push < OpenStruct
diff --git a/lib/rack/tracker/handler.rb b/lib/rack/tracker/handler.rb
index 25c7788..0a3d869 100644
--- a/lib/rack/tracker/handler.rb
+++ b/lib/rack/tracker/handler.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Rack::Tracker::Handler
   class << self
     def process_track(env, method_name, *args, &block)
diff --git a/lib/rack/tracker/handler_delegator.rb b/lib/rack/tracker/handler_delegator.rb
index f968fa9..99beac8 100644
--- a/lib/rack/tracker/handler_delegator.rb
+++ b/lib/rack/tracker/handler_delegator.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Rack::Tracker::HandlerDelegator
   class << self
     def handler(method_name)
diff --git a/lib/rack/tracker/hotjar/hotjar.rb b/lib/rack/tracker/hotjar/hotjar.rb
index 482e5d3..8635587 100644
--- a/lib/rack/tracker/hotjar/hotjar.rb
+++ b/lib/rack/tracker/hotjar/hotjar.rb
@@ -1,2 +1,4 @@
+# frozen_string_literal: true
+
 class Rack::Tracker::Hotjar < Rack::Tracker::Handler
 end
diff --git a/lib/rack/tracker/javascript_helper.rb b/lib/rack/tracker/javascript_helper.rb
index 02ccdfb..8314563 100644
--- a/lib/rack/tracker/javascript_helper.rb
+++ b/lib/rack/tracker/javascript_helper.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # This module is extracted from Rails to provide reliable javascript escaping.
 #
 # @see https://github.com/rails/rails/blob/master/actionview/lib/action_view/helpers/javascript_helper.rb
@@ -13,8 +15,8 @@ module Rack::Tracker::JavaScriptHelper
       "'" => "\\'"
   }
 
-  JS_ESCAPE_MAP["\342\200\250".force_encoding(Encoding::UTF_8).encode!] = '&#x2028;'
-  JS_ESCAPE_MAP["\342\200\251".force_encoding(Encoding::UTF_8).encode!] = '&#x2029;'
+  JS_ESCAPE_MAP["\342\200\250".dup.force_encoding(Encoding::UTF_8).encode!] = '&#x2028;'
+  JS_ESCAPE_MAP["\342\200\251".dup.force_encoding(Encoding::UTF_8).encode!] = '&#x2029;'
 
   # Escapes carriage returns and single and double quotes for JavaScript segments.
   #
diff --git a/lib/rack/tracker/railtie.rb b/lib/rack/tracker/railtie.rb
index 965cb73..fd1bfbe 100644
--- a/lib/rack/tracker/railtie.rb
+++ b/lib/rack/tracker/railtie.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Rack
   class Tracker
     class Railtie < ::Rails::Railtie
diff --git a/lib/rack/tracker/version.rb b/lib/rack/tracker/version.rb
index 750100f..5a84956 100644
--- a/lib/rack/tracker/version.rb
+++ b/lib/rack/tracker/version.rb
@@ -1,5 +1,7 @@
+# frozen_string_literal: true
+
 module Rack
   class Tracker
-    VERSION = '1.6.0'
+    VERSION = '1.7.0'
   end
 end
diff --git a/lib/rack/tracker/vwo/vwo.rb b/lib/rack/tracker/vwo/vwo.rb
index c7fdfa3..71be6a6 100644
--- a/lib/rack/tracker/vwo/vwo.rb
+++ b/lib/rack/tracker/vwo/vwo.rb
@@ -1,2 +1,4 @@
+# frozen_string_literal: true
+
 class Rack::Tracker::Vwo < Rack::Tracker::Handler
 end
diff --git a/lib/rack/tracker/zanox/zanox.rb b/lib/rack/tracker/zanox/zanox.rb
index a674b6f..49e31db 100644
--- a/lib/rack/tracker/zanox/zanox.rb
+++ b/lib/rack/tracker/zanox/zanox.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Rack::Tracker::Zanox < Rack::Tracker::Handler
 
   # name of the handler
diff --git a/spec/benchmark/tracker_injection_benchmark.rb b/spec/benchmark/tracker_injection_benchmark.rb
index 2874eb1..f986b5e 100644
--- a/spec/benchmark/tracker_injection_benchmark.rb
+++ b/spec/benchmark/tracker_injection_benchmark.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'support/capybara_app_helper'
 require 'benchmark'
 
diff --git a/spec/handler/criteo_spec.rb b/spec/handler/criteo_spec.rb
index 8feded3..b0c526a 100644
--- a/spec/handler/criteo_spec.rb
+++ b/spec/handler/criteo_spec.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 RSpec.describe Rack::Tracker::Criteo do
 
   describe Rack::Tracker::Criteo::Event do
diff --git a/spec/handler/facebook_pixel_spec.rb b/spec/handler/facebook_pixel_spec.rb
index 9716529..e1f28dd 100644
--- a/spec/handler/facebook_pixel_spec.rb
+++ b/spec/handler/facebook_pixel_spec.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 RSpec.describe Rack::Tracker::FacebookPixel do
   def env
     { 'PIXEL_ID' => 'DYNAMIC_PIXEL_ID' }
diff --git a/spec/handler/facebook_spec.rb b/spec/handler/facebook_spec.rb
index 6a24738..bd8f115 100644
--- a/spec/handler/facebook_spec.rb
+++ b/spec/handler/facebook_spec.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 RSpec.describe Rack::Tracker::Facebook do
   describe Rack::Tracker::Facebook::Event do
 
diff --git a/spec/handler/go_squared_spec.rb b/spec/handler/go_squared_spec.rb
index 4d15bab..aebe3c7 100644
--- a/spec/handler/go_squared_spec.rb
+++ b/spec/handler/go_squared_spec.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 RSpec.describe Rack::Tracker::GoSquared do
 
   def env
diff --git a/spec/handler/google_adwords_conversion_spec.rb b/spec/handler/google_adwords_conversion_spec.rb
index 52536cf..fbdbf5a 100644
--- a/spec/handler/google_adwords_conversion_spec.rb
+++ b/spec/handler/google_adwords_conversion_spec.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 RSpec.describe Rack::Tracker::GoogleAdwordsConversion do
 
   def env
diff --git a/spec/handler/google_analytics_spec.rb b/spec/handler/google_analytics_spec.rb
index 027b7a8..e012e3a 100644
--- a/spec/handler/google_analytics_spec.rb
+++ b/spec/handler/google_analytics_spec.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 RSpec.describe Rack::Tracker::GoogleAnalytics do
   def env
     {
diff --git a/spec/handler/google_tag_manager_spec.rb b/spec/handler/google_tag_manager_spec.rb
index ed1e147..a643e47 100644
--- a/spec/handler/google_tag_manager_spec.rb
+++ b/spec/handler/google_tag_manager_spec.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 RSpec.describe Rack::Tracker::GoogleTagManager do
 
   def env
diff --git a/spec/handler/handler_spec.rb b/spec/handler/handler_spec.rb
index 2fabeff..e00e1aa 100644
--- a/spec/handler/handler_spec.rb
+++ b/spec/handler/handler_spec.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 RSpec.describe Rack::Tracker::Handler do
   def env
     { misc: 'foobar' }
diff --git a/spec/handler/hotjar_spec.rb b/spec/handler/hotjar_spec.rb
index c4a5855..698df29 100644
--- a/spec/handler/hotjar_spec.rb
+++ b/spec/handler/hotjar_spec.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 RSpec.describe Rack::Tracker::Hotjar do
   def env
     { foo: 'bar' }
diff --git a/spec/handler/vwo_spec.rb b/spec/handler/vwo_spec.rb
index 5b4fab6..4b03f87 100644
--- a/spec/handler/vwo_spec.rb
+++ b/spec/handler/vwo_spec.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 RSpec.describe Rack::Tracker::Vwo do
 
   def env
diff --git a/spec/handler/zanox_spec.rb b/spec/handler/zanox_spec.rb
index dbf374d..438eb5c 100644
--- a/spec/handler/zanox_spec.rb
+++ b/spec/handler/zanox_spec.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 RSpec.describe Rack::Tracker::Zanox do
 
   describe Rack::Tracker::Zanox::Sale do
diff --git a/spec/integration/criteo_integration_spec.rb b/spec/integration/criteo_integration_spec.rb
index aa3df67..9c8977a 100644
--- a/spec/integration/criteo_integration_spec.rb
+++ b/spec/integration/criteo_integration_spec.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'support/capybara_app_helper'
 
 RSpec.describe "Criteo Integration" do
diff --git a/spec/integration/facebook_integration_spec.rb b/spec/integration/facebook_integration_spec.rb
index 456359a..dd9f416 100644
--- a/spec/integration/facebook_integration_spec.rb
+++ b/spec/integration/facebook_integration_spec.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'support/capybara_app_helper'
 
 RSpec.describe "Facebook Integration" do
diff --git a/spec/integration/facebook_pixel_integration_spec.rb b/spec/integration/facebook_pixel_integration_spec.rb
index 07af9f0..03b0586 100644
--- a/spec/integration/facebook_pixel_integration_spec.rb
+++ b/spec/integration/facebook_pixel_integration_spec.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'support/capybara_app_helper'
 
 RSpec.describe "Facebook Pixel Integration" do
diff --git a/spec/integration/go_squared_integration_spec.rb b/spec/integration/go_squared_integration_spec.rb
index d530c6d..d3f8b51 100644
--- a/spec/integration/go_squared_integration_spec.rb
+++ b/spec/integration/go_squared_integration_spec.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'support/capybara_app_helper'
 
 RSpec.describe "GoSquared Integration" do
diff --git a/spec/integration/google_adwords_conversion_integration_spec.rb b/spec/integration/google_adwords_conversion_integration_spec.rb
index 2e64ce9..8e93bc7 100644
--- a/spec/integration/google_adwords_conversion_integration_spec.rb
+++ b/spec/integration/google_adwords_conversion_integration_spec.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'support/capybara_app_helper'
 
 RSpec.describe "Google Adwords Conversion Integration" do
diff --git a/spec/integration/google_analytics_integration_spec.rb b/spec/integration/google_analytics_integration_spec.rb
index 7f5888a..5bffdaa 100644
--- a/spec/integration/google_analytics_integration_spec.rb
+++ b/spec/integration/google_analytics_integration_spec.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'support/capybara_app_helper'
 
 RSpec.describe "Google Analytics Integration" do
diff --git a/spec/integration/google_tag_manager_integration_spec.rb b/spec/integration/google_tag_manager_integration_spec.rb
index f8fe375..5b9dc12 100644
--- a/spec/integration/google_tag_manager_integration_spec.rb
+++ b/spec/integration/google_tag_manager_integration_spec.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'support/capybara_app_helper'
 
 RSpec.describe "Google Tag Manager Integration" do
diff --git a/spec/integration/hotjar_integration_spec.rb b/spec/integration/hotjar_integration_spec.rb
index 301a801..e176a67 100644
--- a/spec/integration/hotjar_integration_spec.rb
+++ b/spec/integration/hotjar_integration_spec.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'support/capybara_app_helper'
 
 RSpec.describe "Hotjar Integration" do
diff --git a/spec/integration/rails_integration_spec.rb b/spec/integration/rails_integration_spec.rb
index 368efbe..f1c3b49 100644
--- a/spec/integration/rails_integration_spec.rb
+++ b/spec/integration/rails_integration_spec.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'support/capybara_app_helper'
 
 RSpec.describe "Rails Integration" do
diff --git a/spec/integration/vwo_integration_spec.rb b/spec/integration/vwo_integration_spec.rb
index 80807ce..366511b 100644
--- a/spec/integration/vwo_integration_spec.rb
+++ b/spec/integration/vwo_integration_spec.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'support/capybara_app_helper'
 
 RSpec.describe "VWO Integration" do
diff --git a/spec/integration/zanox_integration_spec.rb b/spec/integration/zanox_integration_spec.rb
index b1f5f4b..fe8fa21 100644
--- a/spec/integration/zanox_integration_spec.rb
+++ b/spec/integration/zanox_integration_spec.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'support/capybara_app_helper'
 
 RSpec.describe "Zanox Integration" do
diff --git a/spec/spec_helper.rb b/spec/spec_helper.rb
index 39b3f24..c0d276d 100644
--- a/spec/spec_helper.rb
+++ b/spec/spec_helper.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 $LOAD_PATH.unshift(File.join(File.dirname(__FILE__), '..', 'lib'))
 $LOAD_PATH.unshift(File.dirname(__FILE__))
 
diff --git a/spec/support/capybara_app_helper.rb b/spec/support/capybara_app_helper.rb
index 3125e9c..354870d 100644
--- a/spec/support/capybara_app_helper.rb
+++ b/spec/support/capybara_app_helper.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'support/metal_controller'
 
 # helper to configure the middleware stack with custom handlers
diff --git a/spec/support/fake_handler.rb b/spec/support/fake_handler.rb
index c40c1e5..d17c4f2 100644
--- a/spec/support/fake_handler.rb
+++ b/spec/support/fake_handler.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class TrackAllTheThings < Rack::Tracker::Handler
   def render
     Tilt.new( File.join( File.dirname(__FILE__), '../fixtures/track_all_the_things.erb') ).render(self)
diff --git a/spec/support/metal_controller.rb b/spec/support/metal_controller.rb
index b7241c7..4a4c335 100644
--- a/spec/support/metal_controller.rb
+++ b/spec/support/metal_controller.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'action_controller'
 
 class MetalController < ActionController::Metal
diff --git a/spec/tracker/controller_spec.rb b/spec/tracker/controller_spec.rb
index 52d30b2..6f523ff 100644
--- a/spec/tracker/controller_spec.rb
+++ b/spec/tracker/controller_spec.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 TestController = Struct.new(:env) do
   include Rack::Tracker::Controller
 
diff --git a/spec/tracker/handler_delegator_spec.rb b/spec/tracker/handler_delegator_spec.rb
index 2fa2bb8..0e7afd3 100644
--- a/spec/tracker/handler_delegator_spec.rb
+++ b/spec/tracker/handler_delegator_spec.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 Foo = Class.new
 Bar = Class.new
 
diff --git a/spec/tracker/handler_set_spec.rb b/spec/tracker/handler_set_spec.rb
index e3f411c..f69dff2 100644
--- a/spec/tracker/handler_set_spec.rb
+++ b/spec/tracker/handler_set_spec.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Dummy < Rack::Tracker::Handler
 end
 
diff --git a/spec/tracker/javascript_helper_spec.rb b/spec/tracker/javascript_helper_spec.rb
index fc36815..787661c 100644
--- a/spec/tracker/javascript_helper_spec.rb
+++ b/spec/tracker/javascript_helper_spec.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 RSpec.describe Rack::Tracker do
 
   let(:escaper) do
@@ -39,13 +41,11 @@
     it { should escape(%(This "thing" is really\n netos')).to %(This \\"thing\\" is really\\n netos\\') }
     it { should escape(%(backslash\\test)).to %(backslash\\\\test) }
     it { should escape(%(dont </close> tags)).to %(dont <\\/close> tags) }
-    it { should escape(%(unicode \342\200\250 newline).force_encoding(Encoding::UTF_8).encode!).to %(unicode &#x2028; newline) }
-    it { should escape(%(unicode \342\200\251 newline).force_encoding(Encoding::UTF_8).encode!).to %(unicode &#x2029; newline) }
+    it { should escape(%(unicode \342\200\250 newline).dup.force_encoding(Encoding::UTF_8).encode!).to %(unicode &#x2028; newline) }
+    it { should escape(%(unicode \342\200\251 newline).dup.force_encoding(Encoding::UTF_8).encode!).to %(unicode &#x2029; newline) }
 
     it 'works with symbols' do
       expect(subject).to escape(:dimension1).to 'dimension1'
     end
-
   end
-
-end
\ No newline at end of file
+end
diff --git a/spec/tracker/tracker_spec.rb b/spec/tracker/tracker_spec.rb
index 664e6c1..38caa8c 100644
--- a/spec/tracker/tracker_spec.rb
+++ b/spec/tracker/tracker_spec.rb
@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+
 class DummyHandler < Rack::Tracker::Handler
   def render
     Tilt.new( File.join( File.dirname(__FILE__), '../fixtures/dummy.erb') ).render(self)