diff --git a/CHANGELOG.md b/CHANGELOG.md
index c8479a4..3d7bb2e 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,8 @@
+## 1.1.0
+
+* Add `external` option that allows the user to whitelist specific external
+  modules to be included in with documentation.
+
 ## 1.0.7
 
 * Fixes sorting order of documentation
diff --git a/index.js b/index.js
index fb5b1b0..cfe46c7 100644
--- a/index.js
+++ b/index.js
@@ -20,6 +20,9 @@ var mdeps = require('module-deps'),
  * @name documentation
  * @param {Array<String>|String} indexes files to process
  * @param {Object} options options
+ * @param {Array<string>} options.external a string regex / glob match pattern
+ * that defines what external modules will be whitelisted and included in the
+ * generated documentation.
  * @return {Object} stream of output
  */
 module.exports = function (indexes, options) {
diff --git a/lib/module-filters.js b/lib/module-filters.js
index e5ca4ee..7951c48 100644
--- a/lib/module-filters.js
+++ b/lib/module-filters.js
@@ -30,6 +30,8 @@ module.exports = {
         // grab the path of the top-level node_modules directory.
         var topNodeModules = path.join(path.dirname(index), 'node_modules');
         return function matchGlob(file, pkg) {
+          // if a module is not found, don't include it.
+          if (!file || !pkg) return false;
           // if package.json specifies a 'main' script, strip that path off
           // the file to get the module's directory.
           // otherwise, just use the dirname of the file.
diff --git a/test/fixture/external.input.js b/test/fixture/external.input.js
index c270a6b..9d7bf6a 100644
--- a/test/fixture/external.input.js
+++ b/test/fixture/external.input.js
@@ -1,2 +1,3 @@
 require('external');
 require('external2');
+require('module-not-found');