diff --git a/examples/multiple-dirs/css/buttons.css b/examples/multiple-dirs/css/buttons.css
new file mode 100644
index 0000000..6938705
--- /dev/null
+++ b/examples/multiple-dirs/css/buttons.css
@@ -0,0 +1,23 @@
+/**
+ * Buttons
+ *
+ * The Button `.btn` class can be applied to `<button>`, `<input>`, or `<a>` elements.
+ *
+ * @section
+ *
+ * @example
+ * <button class="btn">Button</button>
+ * <input type="submit" class="btn" value="Input"/>
+ * <a href="#" class="btn">Anchor</a>
+ */
+.btn {
+  background-color: #ddd;
+  border-radius: 4px;
+  border: 2px solid transparent;
+  color: black;
+  display: inline-block;
+  font-size: 16px;
+  line-height: 1;
+  padding: 5px 15px;
+  text-decoration: none;
+}
diff --git a/examples/multiple-dirs/index.js b/examples/multiple-dirs/index.js
new file mode 100644
index 0000000..8e423d7
--- /dev/null
+++ b/examples/multiple-dirs/index.js
@@ -0,0 +1,16 @@
+var path = require('path');
+
+var livingcss = require('../../index');
+
+(async function() {
+  try {
+    // all these methods should work:
+    await livingcss('css/buttons.css', 'styleguide');
+    // await livingcss(path.join(__dirname, 'css/buttons.css'), 'styleguide');
+    // await livingcss(path.join(__dirname, 'css/buttons.css'), path.join(__dirname, 'styleguide'));
+    // await livingcss('css/buttons.css', path.join(__dirname, 'styleguide'));
+  } catch (err) {
+    console.error(err);
+    console.error(err.stack);
+  }
+})();
diff --git a/lib/generate.js b/lib/generate.js
index e8a8341..8f79ddd 100644
--- a/lib/generate.js
+++ b/lib/generate.js
@@ -55,13 +55,30 @@ function generate(dest, template, context, options) {
   }
 
   return preprocess
-    .then(function() {
+    .then(async function() {
       // inline all stylesheets for polymer shared styles to work
       // @see https://www.polymer-project.org/1.0/docs/devguide/styling#style-modules
-      return utils.readFiles(context.stylesheets, function(data, file) {
+
+      const parsedStylesheetFile = function(data, file) {
         context.parsedStylesheets = context.parsedStylesheets || [];
         context.parsedStylesheets.push(utils.fixSVGIssue(data));
-      });
+      };
+
+      let fileList;
+      try {
+        fileList = await utils.readFiles(context.stylesheets, parsedStylesheetFile);
+      } catch (err) {
+        if ('ENOENT' !== err.code) {
+          throw err;
+        }
+        const destDir = path.dirname(dest);
+        const stylesheets = context.stylesheets.map((file) => {
+          return path.resolve(destDir, file);
+        });
+        fileList = await utils.readFiles(stylesheets, parsedStylesheetFile);
+      }
+
+      return fileList;
     })
     .then(function success() {
       var html = Handlebars.compile(template)(context);
@@ -94,4 +111,4 @@ function generate(dest, template, context, options) {
     });
 }
 
-module.exports = generate;
\ No newline at end of file
+module.exports = generate;
diff --git a/lib/utils.js b/lib/utils.js
index 5b778dd..4857d2d 100644
--- a/lib/utils.js
+++ b/lib/utils.js
@@ -16,9 +16,8 @@ utils._readFileWithPromise = function readFileWithPromise(file) {
   return new Promise((resolve, reject) => {
     fs.readFile(file, 'utf8', function(err, data) {
       if (err) {
-        reject(err);
+        return reject(err);
       }
-
       resolve(data);
     });
   });
@@ -29,11 +28,11 @@ utils._readFileWithPromise = function readFileWithPromise(file) {
  * @param {string} pattern - Glob file pattern
  * @returns Promise
  */
-function globWithPromsie(pattern) {
+function globWithPromise(pattern) {
   return new Promise((resolve, reject) => {
     glob(pattern, function(err, files) {
       if (err) {
-        reject(err);
+        return reject(err);
       }
 
       if (files.length === 0) {
@@ -153,7 +152,7 @@ utils.sortCategoryBy = function sortCategoryBy(categories, sortOrder) {
 utils.readFileGlobs = async function readFileGlobs(patterns, callback) {
   patterns = (!Array.isArray(patterns) ? [patterns] : patterns);
   let globPromises = await patterns.map(async (pattern) => {
-    return globWithPromsie(pattern);
+    return globWithPromise(pattern);
   });
 
   return Promise.all(globPromises)
@@ -162,7 +161,7 @@ utils.readFileGlobs = async function readFileGlobs(patterns, callback) {
       // fileList is an array of arrays of files
       // e.g. [ [fileOne, fileTwo], [fileThree, fileFour], ...]
       let readFilePromises = await fileList.map(async (files) => {
-        return await utils.readFiles(files)
+        return await utils.readFiles(files);
       });
 
       return Promise.all(readFilePromises);
@@ -187,24 +186,27 @@ utils.readFileGlobs = async function readFileGlobs(patterns, callback) {
  * @param {function} callback - Callback to execute for each read file.
  * @returns {Promise}
  */
-utils.readFiles = async function readFiles(files, callback) {
-  if (!files || (Array.isArray(files) && !files.length)) return Promise.resolve();
+utils.readFiles = function readFiles(files, callback) {
+  if (!files || (Array.isArray(files) && !files.length)) return Promise.resolve([]);
 
   files = (!Array.isArray(files) ? [files] : files);
-  let promises = await Promise.all(files.map(async (file) => {
+  return Promise.all(files.map(async (file) => {
     let data = await utils._readFileWithPromise(file);
     return [data, file];
-  }));
-
-  return Promise.all(promises).then(files => {
-    if (callback) {
-      files.forEach(function(data) {
-        callback.apply(null, data);
-      });
-    }
-
-    return files;
-  })
+  }))
+    .then(async files => {
+      if (callback) {
+        const promises = [];
+        files.forEach(function(data) {
+          const result = callback.apply(null, data);
+          if ('object' === typeof result && result.then) {
+            promises.push(result);
+          }
+        });
+        await Promise.all(promises);
+      }
+      return files;
+    });
 }
 
 /**
diff --git a/package-lock.json b/package-lock.json
index e8e3826..e98dca2 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -895,6 +895,15 @@
         "type-detect": "^4.0.5"
       }
     },
+    "chai-as-promised": {
+      "version": "7.1.1",
+      "resolved": "https://registry.npmjs.org/chai-as-promised/-/chai-as-promised-7.1.1.tgz",
+      "integrity": "sha512-azL6xMoi+uxu6z4rhWQ1jbdUhOMhis2PvscD/xjLqNMkv3BPPp2JyyuTHOrf9BOosGpNQ11v6BKv/g57RXbiaA==",
+      "dev": true,
+      "requires": {
+        "check-error": "^1.0.2"
+      }
+    },
     "chalk": {
       "version": "1.1.3",
       "resolved": "https://registry.npmjs.org/chalk/-/chalk-1.1.3.tgz",
@@ -2180,7 +2189,8 @@
         "ansi-regex": {
           "version": "2.1.1",
           "bundled": true,
-          "dev": true
+          "dev": true,
+          "optional": true
         },
         "aproba": {
           "version": "1.2.0",
@@ -2201,12 +2211,14 @@
         "balanced-match": {
           "version": "1.0.0",
           "bundled": true,
-          "dev": true
+          "dev": true,
+          "optional": true
         },
         "brace-expansion": {
           "version": "1.1.11",
           "bundled": true,
           "dev": true,
+          "optional": true,
           "requires": {
             "balanced-match": "^1.0.0",
             "concat-map": "0.0.1"
@@ -2221,17 +2233,20 @@
         "code-point-at": {
           "version": "1.1.0",
           "bundled": true,
-          "dev": true
+          "dev": true,
+          "optional": true
         },
         "concat-map": {
           "version": "0.0.1",
           "bundled": true,
-          "dev": true
+          "dev": true,
+          "optional": true
         },
         "console-control-strings": {
           "version": "1.1.0",
           "bundled": true,
-          "dev": true
+          "dev": true,
+          "optional": true
         },
         "core-util-is": {
           "version": "1.0.2",
@@ -2348,7 +2363,8 @@
         "inherits": {
           "version": "2.0.3",
           "bundled": true,
-          "dev": true
+          "dev": true,
+          "optional": true
         },
         "ini": {
           "version": "1.3.5",
@@ -2360,6 +2376,7 @@
           "version": "1.0.0",
           "bundled": true,
           "dev": true,
+          "optional": true,
           "requires": {
             "number-is-nan": "^1.0.0"
           }
@@ -2374,6 +2391,7 @@
           "version": "3.0.4",
           "bundled": true,
           "dev": true,
+          "optional": true,
           "requires": {
             "brace-expansion": "^1.1.7"
           }
@@ -2381,12 +2399,14 @@
         "minimist": {
           "version": "0.0.8",
           "bundled": true,
-          "dev": true
+          "dev": true,
+          "optional": true
         },
         "minipass": {
           "version": "2.3.5",
           "bundled": true,
           "dev": true,
+          "optional": true,
           "requires": {
             "safe-buffer": "^5.1.2",
             "yallist": "^3.0.0"
@@ -2405,6 +2425,7 @@
           "version": "0.5.1",
           "bundled": true,
           "dev": true,
+          "optional": true,
           "requires": {
             "minimist": "0.0.8"
           }
@@ -2485,7 +2506,8 @@
         "number-is-nan": {
           "version": "1.0.1",
           "bundled": true,
-          "dev": true
+          "dev": true,
+          "optional": true
         },
         "object-assign": {
           "version": "4.1.1",
@@ -2497,6 +2519,7 @@
           "version": "1.4.0",
           "bundled": true,
           "dev": true,
+          "optional": true,
           "requires": {
             "wrappy": "1"
           }
@@ -2582,7 +2605,8 @@
         "safe-buffer": {
           "version": "5.1.2",
           "bundled": true,
-          "dev": true
+          "dev": true,
+          "optional": true
         },
         "safer-buffer": {
           "version": "2.1.2",
@@ -2618,6 +2642,7 @@
           "version": "1.0.2",
           "bundled": true,
           "dev": true,
+          "optional": true,
           "requires": {
             "code-point-at": "^1.0.0",
             "is-fullwidth-code-point": "^1.0.0",
@@ -2637,6 +2662,7 @@
           "version": "3.0.1",
           "bundled": true,
           "dev": true,
+          "optional": true,
           "requires": {
             "ansi-regex": "^2.0.0"
           }
@@ -2680,12 +2706,14 @@
         "wrappy": {
           "version": "1.0.2",
           "bundled": true,
-          "dev": true
+          "dev": true,
+          "optional": true
         },
         "yallist": {
           "version": "3.0.3",
           "bundled": true,
-          "dev": true
+          "dev": true,
+          "optional": true
         }
       }
     },
diff --git a/package.json b/package.json
index 025dae6..e462c69 100644
--- a/package.json
+++ b/package.json
@@ -1,27 +1,37 @@
 {
-  "name": "livingcss",
-  "version": "6.0.3",
-  "description": "Generate a style guide using comment driven content creation",
-  "main": "index.js",
-  "scripts": {
-    "test": "nyc --reporter=lcov --reporter=text mocha"
+  "_from": "livingcss",
+  "_id": "livingcss@6.0.3",
+  "_inBundle": false,
+  "_integrity": "sha512-CqClAsCzLbwePqpFfieEvwNgevgSLCbCcTFvGnlP2ewvVcVa8dmKtdtcYt+DrOjCpoTYgzKnpgyhhfiCDjdZkQ==",
+  "_location": "/livingcss",
+  "_phantomChildren": {},
+  "_requested": {
+    "type": "tag",
+    "registry": true,
+    "raw": "livingcss",
+    "name": "livingcss",
+    "escapedName": "livingcss",
+    "rawSpec": "",
+    "saveSpec": null,
+    "fetchSpec": "latest"
   },
-  "repository": {
-    "type": "git",
-    "url": "https://github.com/straker/livingcss.git"
-  },
-  "keywords": [
-    "style",
-    "guide",
-    "generator",
-    "css"
+  "_requiredBy": [
+    "#DEV:/",
+    "#USER"
   ],
-  "author": "Steven Lambert <steven@sklambert.com> (http://sklambert.com/)",
-  "license": "MIT",
+  "_resolved": "https://registry.npmjs.org/livingcss/-/livingcss-6.0.3.tgz",
+  "_shasum": "7f2eeb07dd42734029f2962ad1b8751cab252eb2",
+  "_spec": "livingcss",
+  "_where": "/Users/matmar10/Projects/Blossom/bootstrap-theme",
+  "author": {
+    "name": "Steven Lambert",
+    "email": "steven@sklambert.com",
+    "url": "http://sklambert.com/"
+  },
   "bugs": {
     "url": "https://github.com/straker/livingcss/issues"
   },
-  "homepage": "https://github.com/straker/livingcss",
+  "bundleDependencies": false,
   "dependencies": {
     "comment-parser": "^0.5.4",
     "glob": "^7.1.3",
@@ -31,8 +41,11 @@
     "mkdirp": "^0.5.1",
     "normalize-newline": "^3.0.0"
   },
+  "deprecated": false,
+  "description": "Generate a style guide using comment driven content creation",
   "devDependencies": {
     "chai": "^4.2.0",
+    "chai-as-promised": "^7.1.1",
     "coveralls": "^3.0.3",
     "gulp": "^4.0.1",
     "gulp-connect": "^5.7.0",
@@ -49,5 +62,23 @@
     "nyc": "^14.1.0",
     "proxyquire": "^1.8.0",
     "sinon": "^4.2.2"
-  }
+  },
+  "homepage": "https://github.com/straker/livingcss",
+  "keywords": [
+    "style",
+    "guide",
+    "generator",
+    "css"
+  ],
+  "license": "MIT",
+  "main": "index.js",
+  "name": "livingcss",
+  "repository": {
+    "type": "git",
+    "url": "git+https://github.com/straker/livingcss.git"
+  },
+  "scripts": {
+    "test": "nyc --reporter=lcov --reporter=text mocha"
+  },
+  "version": "6.0.3"
 }
diff --git a/test/utils.spec.js b/test/utils.spec.js
index 8065031..83dbbcb 100644
--- a/test/utils.spec.js
+++ b/test/utils.spec.js
@@ -1,10 +1,14 @@
 /*jshint -W030 */
 
-var expect = require('chai').expect;
+var chai = require('chai');
+var chaiAsPromised = require('chai-as-promised');
 var sinon = require('sinon');
 var proxyquire = require('proxyquire');
 var normalizeNewline = require('normalize-newline');
 
+chai.use(chaiAsPromised);
+var expect = chai.expect;
+
 // stubs
 var fsStub = {
   writeFile: function(file, data, options, callback) { callback(null); },
@@ -18,7 +22,7 @@ var globStub = function(files, callback) {
   if (files instanceof Error) return callback(files);
   files = (!Array.isArray(files) ? [files] : files);
   callback(null, files);
-}
+};
 
 var utils = proxyquire('../lib/utils', {
   fs: fsStub,
@@ -243,16 +247,14 @@ describe('utils', function() {
       });
     });
 
-    it('should handle error', function(done) {
-      var file = new Error('custom cannot read file');
+    it('should notify of error', function() {
+      var promise = utils.readFiles(new Error('custom cannot read file'));
+      return expect(promise).to.eventually.be.rejectedWith(Error);
+    });
 
-      utils.readFiles(file)
-      .then(function() {
-        done('readFiles did not throw error');
-      })
-      .catch(function(err) {
-        done();
-      });
+    it('should return empty array if no files', function() {
+      var promise = utils.readFiles([]);
+      return expect(promise).to.eventually.deep.equal([]);
     });
 
   });
@@ -341,30 +343,15 @@ describe('utils', function() {
       });
     });
 
-    it('should handle glob error', function(done) {
-      var files = new Error('custom: glob error');
-
-      utils.readFileGlobs(files)
-      .then(function() {
-        done('readFileGlobs did not throw error');
-      })
-      .catch(function(err) {
-        expect(err.message).to.equal('custom: glob error');
-        done();
-      });
+    it('should handle glob error', async function() {
+      var promise = utils.readFileGlobs(new Error('custom: glob error'));
+      return expect(promise).to.be.rejectedWith(Error);
     });
 
-    it('should handle read file error', function(done) {
+    it('should handle read file error', function() {
       var files = '__ERROR__';
-
-      utils.readFileGlobs(files)
-      .then(function() {
-        done('readFileGlobs did not throw error');
-      })
-      .catch(function(err) {
-        expect(err).to.equal('readFile error');
-        done();
-      });
+      var promise = utils.readFileGlobs(files);
+      return expect(promise).to.be.rejected;
     });
 
   });
@@ -402,4 +389,4 @@ describe('utils', function() {
       expect(utils.fixSVGIssue(testString)).to.equal(testString);
     });
   });
-});
\ No newline at end of file
+});