diff --git a/.travis.yml b/.travis.yml
new file mode 100644
index 0000000..e08b7c4
--- /dev/null
+++ b/.travis.yml
@@ -0,0 +1,6 @@
+language: node_js
+node_js:
+  - "stable"
+  - "10"
+  - "8"
+  - "6"
diff --git a/index.js b/index.js
index e699ddb..c17dce8 100644
--- a/index.js
+++ b/index.js
@@ -14,7 +14,7 @@ function transform (filename, source, options, done) {
   const plugins = defined(options.plugins, [])
     .map(plugin => {
       if (typeof plugin === 'string') {
-        plugin = [ plugin ]
+        plugin = [plugin]
       }
 
       return {
@@ -36,13 +36,27 @@ function transform (filename, source, options, done) {
   delete ctx.plugins
 
   postcssrc(ctx, basedir).then(compile, function () {
-    return compile({options: ctx})
+    return compile({ options: ctx })
   }).then(function (result) {
-    done(null, result.css)
+    done(null, result)
   }, done)
 
   function compile (config) {
     return postcss(plugins.concat(config.plugins).filter(Boolean))
       .process(source, config.options)
+      .then(function (result) {
+        // Collect imported files for watchify
+        const files = [filename]
+        result.messages.forEach(function (msg) {
+          if (msg.type === 'dependency') {
+            files.push(msg.file)
+          }
+        })
+
+        return {
+          css: result.css,
+          files: files
+        }
+      })
   }
 }
diff --git a/package.json b/package.json
index b270e10..f787b49 100644
--- a/package.json
+++ b/package.json
@@ -22,20 +22,21 @@
   },
   "homepage": "https://github.com/stackcss/sheetify-postcss#readme",
   "devDependencies": {
-    "browserify": "^13.1.0",
-    "dependency-check": "^2.6.0",
-    "npm-run-all": "^3.0.0",
-    "postcss-color-function": "^2.0.1",
+    "browserify": "^16.0.0",
+    "dependency-check": "^3.4.1",
+    "npm-run-all": "^4.1.5",
+    "postcss-color-function": "^4.0.1",
+    "postcss-import": "^12.0.1",
     "pull-test": "^1.2.3",
-    "sheetify": "^5.1.0",
-    "standard": "^8.0.0",
-    "tape": "^4.5.1"
+    "sheetify": "^7.2.0",
+    "standard": "^13.0.2",
+    "tape": "^4.11.0"
   },
   "dependencies": {
     "defined": "^1.0.0",
-    "postcss": "^5.1.2",
-    "postcss-load-config": "^1.2.0",
-    "resolve": "^1.1.7",
-    "xtend": "^4.0.1"
+    "postcss": "^7.0.17",
+    "postcss-load-config": "^2.1.0",
+    "resolve": "^1.11.1",
+    "xtend": "^4.0.2"
   }
 }
diff --git a/test/index.js b/test/index.js
index a29e633..a2bddb5 100644
--- a/test/index.js
+++ b/test/index.js
@@ -6,28 +6,40 @@ test(function (t) {
   t.test('module should work with postcss plugins without options', function (t) {
     t.plan(2)
 
-    sheetifyPostcss('test.css', '.rule {}', { basedir: __dirname, plugins: [ './stubs/postcss-plugin' ] }, (err, css) => {
+    sheetifyPostcss('test.css', '.rule {}', { basedir: __dirname, plugins: ['./stubs/postcss-plugin'] }, (err, result) => {
       t.equal(err, null)
-      t.equal(css, '.ok {}')
+      t.equal(result.css, '.ok {}')
     })
   })
 
   t.test('module should work with postcss plugins and their options', function (t) {
     t.plan(2)
 
-    sheetifyPostcss('test.css', '.rule {}', { basedir: __dirname, plugins: [ [ './stubs/postcss-plugin', { has: true } ] ] }, (err, css) => {
+    sheetifyPostcss('test.css', '.rule {}', { basedir: __dirname, plugins: [['./stubs/postcss-plugin', { has: true }]] }, (err, result) => {
       t.equal(err, null)
-      t.equal(css, '.ok-with-options {}')
+      t.equal(result.css, '.ok-with-options {}')
     })
   })
 
   t.test('module should respect postcssrc config file', function (t) {
     t.plan(2)
 
-    sheetifyPostcss('test.css', '.rule {}', { basedir: path.join(__dirname, 'stubs') }, (err, css) => {
+    sheetifyPostcss('test.css', '.rule {}', { basedir: path.join(__dirname, 'stubs') }, (err, result) => {
       t.equal(err, null)
-      t.equal(css, '.ok-with-postcssrc {}')
+      t.equal(result.css, '.ok-with-postcssrc {}')
     })
   })
-})
 
+  t.test('should report imported files if postcss-import is used', function (t) {
+    t.plan(3)
+
+    sheetifyPostcss(path.join(__dirname, 'test.css'), '@import "./stubs/dep.css"', { basedir: __dirname, plugins: ['postcss-import'] }, (err, result) => {
+      t.equal(err, null)
+      t.equal(result.css, '.dependency {}')
+      t.deepEqual(result.files, [
+        path.join(__dirname, 'test.css'),
+        path.join(__dirname, 'stubs/dep.css')
+      ])
+    })
+  })
+})
diff --git a/test/stubs/dep.css b/test/stubs/dep.css
new file mode 100644
index 0000000..e7b7702
--- /dev/null
+++ b/test/stubs/dep.css
@@ -0,0 +1 @@
+.dependency {}