diff --git a/README.md b/README.md
index 335719c..c35e0e9 100644
--- a/README.md
+++ b/README.md
@@ -20,6 +20,7 @@ by github or other sites via a command line flag.
   - [Specifying a custom TOC title](#specifying-a-custom-toc-title)
   - [Specifying a minimum heading level for TOC entries](#specifying-a-minimum-heading-level-for-toc-entries)
   - [Specifying a maximum heading level for TOC entries](#specifying-a-maximum-heading-level-for-toc-entries)
+  - [Performing a dry run](#performing-a-dry-run)
   - [Printing to stdout](#printing-to-stdout)
   - [Only update existing ToC](#only-update-existing-toc)
   - [Usage as a `git` hook](#usage-as-a-git-hook)
@@ -140,6 +141,11 @@ By default,
 - no limit is placed on Markdown-formatted headings,
 - whereas headings from embedded HTML are limited to 4 levels.
 
+### Performing a dry run
+
+Use the `--dryrun` option to not write changes to files but instead return an exit code of 1 to indicates files are out of date and should be updated.
+This is useful CI environments where you want to check if your docs are up to date as part of your build process.
+
 ### Printing to stdout
 
 You can print to stdout by using the `-s` or `--stdout` option.
diff --git a/doctoc.js b/doctoc.js
index c3a85f8..d5247ec 100755
--- a/doctoc.js
+++ b/doctoc.js
@@ -15,7 +15,7 @@ function cleanPath(path) {
   return homeExpanded;
 }
 
-function transformAndSave(files, mode, maxHeaderLevel, minHeaderLevel, title, notitle, entryPrefix, processAll, stdOut, updateOnly) {
+function transformAndSave(files, mode, maxHeaderLevel, minHeaderLevel, title, notitle, entryPrefix, processAll, stdOut, updateOnly, dryRun) {
   if (processAll) {
     console.log('--all flag is enabled. Including headers before the TOC location.')
   }
@@ -44,17 +44,28 @@ function transformAndSave(files, mode, maxHeaderLevel, minHeaderLevel, title, no
   }
 
   unchanged.forEach(function (x) {
-    console.log('"%s" is up to date', x.path);
+    if (stdOut) {
+      console.log('==================\n\n"%s" is up to date', x.path)
+    }
+    else {
+      console.log('"%s" is up to date', x.path);
+    }
   });
 
   changed.forEach(function (x) { 
     if (stdOut) {
       console.log('==================\n\n"%s" should be updated', x.path)
-    } else {
+    } else if (dryRun) {
+      console.log('"%s" should be updated but wasn\'t due to dry run.', x.path);
+    }
+    else {
       console.log('"%s" will be updated', x.path);
       fs.writeFileSync(x.path, x.data, 'utf8');
     }
   });
+  if (dryRun && changed.length > 0) {
+    process.exitCode = 1;
+  }
 }
 
 function printUsageAndExit(isErr) {
@@ -82,7 +93,7 @@ var modes = {
 var mode = modes['github'];
 
 var argv = minimist(process.argv.slice(2)
-    , { boolean: [ 'h', 'help', 'T', 'notitle', 's', 'stdout', 'all' , 'u', 'update-only'].concat(Object.keys(modes))
+    , { boolean: [ 'h', 'help', 'T', 'notitle', 's', 'stdout', 'all' , 'u', 'update-only', 'd', 'dryrun'].concat(Object.keys(modes))
     , string: [ 'title', 't', 'maxlevel', 'm', 'minlevel', 'n', 'entryprefix' ]
     , unknown: function(a) { return (a[0] == '-' ? (console.error('Unknown option(s): ' + a), printUsageAndExit(true)) : true); }
     });
@@ -103,6 +114,7 @@ var entryPrefix = argv.entryprefix || '-';
 var processAll = argv.all;
 var stdOut = argv.s || argv.stdout
 var updateOnly = argv.u || argv['update-only']
+var dryRun = argv.d || argv.dryrun || false;
 
 var maxHeaderLevel = argv.m || argv.maxlevel;
 if (maxHeaderLevel && isNaN(maxHeaderLevel)) { console.error('Max. heading level specified is not a number: ' + maxHeaderLevel), printUsageAndExit(true); }
@@ -126,9 +138,14 @@ for (var i = 0; i < argv._.length; i++) {
     files = [{ path: target }];
   }
 
-  transformAndSave(files, mode, maxHeaderLevel, minHeaderLevel, title, notitle, entryPrefix, processAll, stdOut, updateOnly);
+  transformAndSave(files, mode, maxHeaderLevel, minHeaderLevel, title, notitle, entryPrefix, processAll, stdOut, updateOnly, dryRun);
 
-  console.log('\nEverything is OK.');
+  if (dryRun && process.exitCode === 1) {
+    console.log('\nDocumentation tables of contents are out of date.');
+  }
+  else {
+    console.log('\nEverything is OK.');
+  }
 }
 
 module.exports.transform = transform;
diff --git a/lib/transform.js b/lib/transform.js
index 3a29f60..e2fbd05 100644
--- a/lib/transform.js
+++ b/lib/transform.js
@@ -164,10 +164,11 @@ exports = module.exports = function transform(content, mode, maxHeaderLevel, min
 
   var wrappedToc =  start + '\n' + toc + '\n' + end;
 
-  if (currentToc === toc) return { transformed: false };
-
-  var data = updateSection(lines.join('\n'), wrappedToc, matchesStart, matchesEnd, true);
-  return { transformed : true, data : data, toc: toc, wrappedToc: wrappedToc };
+  var data;
+  if (currentToc != wrappedToc){
+    data = updateSection(lines.join('\n'), wrappedToc, matchesStart, matchesEnd, true);
+  }
+  return { transformed : currentToc != wrappedToc, data : data, toc: toc, wrappedToc: wrappedToc };
 };
 
 exports.start = start;
diff --git a/test/fixtures/readme-with-out_of_date_toc.md b/test/fixtures/readme-with-out_of_date_toc.md
new file mode 100644
index 0000000..bf140c7
--- /dev/null
+++ b/test/fixtures/readme-with-out_of_date_toc.md
@@ -0,0 +1,19 @@
+# Hello, world!
+
+README to test doctoc with user-specified titles.
+
+<!-- START doctoc generated TOC please keep comment here to allow auto update -->
+<!-- DON'T EDIT THIS SECTION, INSTEAD RE-RUN doctoc TO UPDATE -->
+## Table of Contents
+
+- [Installation](#installation)
+- [API](#api)
+- [License](#license)
+
+<!-- END doctoc generated TOC please keep comment here to allow auto update -->
+
+
+## Installation
+## API
+## Contributing
+## License
diff --git a/test/fixtures/stdout.md b/test/fixtures/stdout.md
index 884a74c..98f60d0 100644
--- a/test/fixtures/stdout.md
+++ b/test/fixtures/stdout.md
@@ -11,6 +11,6 @@ DocToccing single file "test/fixtures/readme-with-custom-title.md" for github.co
 
 ==================
 
-"test/fixtures/readme-with-custom-title.md" should be updated
+"test/fixtures/readme-with-custom-title.md" is up to date
 
 Everything is OK.
diff --git a/test/transform-dryrun.js b/test/transform-dryrun.js
new file mode 100644
index 0000000..40f089c
--- /dev/null
+++ b/test/transform-dryrun.js
@@ -0,0 +1,55 @@
+'use strict';
+/*jshint asi: true */
+
+var test = require('tap').test,
+    fs = require('fs'),
+    exec = require("child_process").exec;
+
+test('\nshould exit with a error code due to --dryrun option', function (t) {
+
+    exec('node doctoc.js test/fixtures/readme-with-out_of_date_toc.md --dryrun', function (error, stdout, stderr) {
+      if (error) {
+        t.deepEqual(error.code, 1, 'process exited with error code 1 as expected');
+        t.end('process did have an error');
+      } else {
+        t.fail('process did not produce an error: ' + error);
+        t.end();
+      }
+    })
+})
+
+test('\nshould exit with no error code with --dryrun option', function (t) {
+
+    exec('node doctoc.js test/fixtures/readme-with-custom-title.md --dryrun', function (error, stdout, stderr) {
+      if (error) {
+        t.fail('process produced an unexpected error: ' + error);
+        t.end()
+      } else {
+        t.end('process did not have an error');
+      }
+    })
+})
+
+test('\nshould exit no error code due to no --dryrun option for out of date toc', function (t) {
+
+    exec('node doctoc.js test/fixtures/readme-with-out_of_date_toc.md --stdout', function (error, stdout, stderr) {
+      if (error) {
+        t.fail('process produced an unexpected error: ' + error);
+        t.end()
+      } else {
+        t.end('process did not have an error');
+      }
+    })
+})
+
+test('\nshould exit with no error code', function (t) {
+
+    exec('node doctoc.js test/fixtures/readme-with-custom-title.md', function (error, stdout, stderr) {
+      if (error) {
+        t.fail('process produced an unexpected error: ' + error);
+        t.end()
+      } else {
+        t.end('process did not have an error');
+      }
+    })
+})