diff --git a/lib/annotate/annotate_routes.rb b/lib/annotate/annotate_routes.rb
index 75cc421e..c9a2218a 100644
--- a/lib/annotate/annotate_routes.rb
+++ b/lib/annotate/annotate_routes.rb
@@ -29,8 +29,7 @@ def do_annotations(options = {})
         content, header_position = Helpers.strip_annotations(existing_text)
         new_content = annotate_routes(HeaderGenerator.generate(options), content, header_position, options)
         new_text = new_content.join("\n")
-
-        if rewrite_contents(existing_text, new_text)
+        if rewrite_contents(existing_text, new_text, options[:frozen])
           puts "#{routes_file} was annotated."
         else
           puts "#{routes_file} was not changed."
@@ -40,13 +39,13 @@ def do_annotations(options = {})
       end
     end
 
-    def remove_annotations(_options={})
+    def remove_annotations(options={})
       if routes_file_exist?
         existing_text = File.read(routes_file)
         content, header_position = Helpers.strip_annotations(existing_text)
         new_content = strip_on_removal(content, header_position)
         new_text = new_content.join("\n")
-        if rewrite_contents(existing_text, new_text)
+        if rewrite_contents(existing_text, new_text, options[:frozen])
           puts "Annotations were removed from #{routes_file}."
         else
           puts "#{routes_file} was not changed (Annotation did not exist)."
@@ -82,13 +81,15 @@ def strip_on_removal(content, header_position)
       content
     end
 
-    def rewrite_contents(existing_text, new_text)
-      if existing_text == new_text
-        false
-      else
+    def rewrite_contents(existing_text, new_text, frozen)
+      content_changed = (existing_text != new_text)
+
+      if content_changed
+        abort "annotate error. #{routes_file} needs to be updated, but annotate was run with `--frozen`." if frozen
         File.open(routes_file, 'wb') { |f| f.puts(new_text) }
-        true
       end
+
+      content_changed
     end
 
     def annotate_routes(header, content, header_position, options = {})
diff --git a/lib/tasks/annotate_routes.rake b/lib/tasks/annotate_routes.rake
index ae682933..b2832d44 100644
--- a/lib/tasks/annotate_routes.rake
+++ b/lib/tasks/annotate_routes.rake
@@ -14,6 +14,7 @@ task :annotate_routes => :environment do
   options[:position_in_routes] = Annotate::Helpers.fallback(ENV['position_in_routes'], ENV['position'])
   options[:ignore_routes] = Annotate::Helpers.fallback(ENV['ignore_routes'],  nil)
   options[:require] = ENV['require'] ? ENV['require'].split(',') : []
+  options[:frozen] = Annotate::Helpers.true?(ENV['frozen'])
   options[:wrapper_open] = Annotate::Helpers.fallback(ENV['wrapper_open'], ENV['wrapper'])
   options[:wrapper_close] = Annotate::Helpers.fallback(ENV['wrapper_close'], ENV['wrapper'])
   AnnotateRoutes.do_annotations(options)
diff --git a/spec/lib/annotate/annotate_routes_spec.rb b/spec/lib/annotate/annotate_routes_spec.rb
index 805aec66..2d27b745 100644
--- a/spec/lib/annotate/annotate_routes_spec.rb
+++ b/spec/lib/annotate/annotate_routes_spec.rb
@@ -556,6 +556,71 @@
         end
       end
     end
+
+    describe 'frozen option' do
+      let :aborted_message do
+        "annotate error. #{ROUTE_FILE} needs to be updated, but annotate was run with `--frozen`."
+      end
+
+      let :rake_routes_result do
+        <<-EOS
+                                Prefix Verb       URI Pattern                                               Controller#Action
+                             myaction1 GET        /url1(.:format)                                           mycontroller1#action
+                             myaction2 POST       /url2(.:format)                                           mycontroller2#action
+                             myaction3 DELETE|GET /url3(.:format)                                           mycontroller3#action
+        EOS
+      end
+
+      before :each do
+        expect(File).to receive(:exist?).with(ROUTE_FILE).and_return(true).once
+        expect(File).to receive(:read).with(ROUTE_FILE).and_return(route_file_content).once
+
+        expect(AnnotateRoutes::HeaderGenerator).to receive(:`).with('rake routes').and_return(rake_routes_result).once
+      end
+
+      context 'when annotation does not exists' do
+        let :route_file_content do
+          ''
+        end
+
+        it 'aborts' do
+          expect { AnnotateRoutes.do_annotations(frozen: true) }.to raise_error SystemExit, aborted_message
+        end
+      end
+
+      context 'when annotation exists but is not updated' do
+        let :route_file_content do
+          <<~EOS
+            # == Route Map
+            #
+            #                                 Prefix Verb       URI Pattern                                               Controller#Action
+            #                              myaction2 POST       /url2(.:format)                                           mycontroller2#action
+            #                              myaction3 DELETE|GET /url3(.:format)                                           mycontroller3#action
+          EOS
+        end
+
+        it 'aborts' do
+          expect { AnnotateRoutes.do_annotations(frozen: true) }.to raise_error SystemExit, aborted_message
+        end
+      end
+
+      context 'when annotation exists and is already updated' do
+        let :route_file_content do
+          <<~EOS
+            # == Route Map
+            #
+            #                                 Prefix Verb       URI Pattern                                               Controller#Action
+            #                              myaction1 GET        /url1(.:format)                                           mycontroller1#action
+            #                              myaction2 POST       /url2(.:format)                                           mycontroller2#action
+            #                              myaction3 DELETE|GET /url3(.:format)                                           mycontroller3#action
+          EOS
+        end
+
+        it 'does NOT abort' do
+          expect { AnnotateRoutes.do_annotations(frozen: true) }.not_to raise_error
+        end
+      end
+    end
   end
 
   describe '.remove_annotations' do