diff --git a/lib/index.js b/lib/index.js
index <HASH>..<HASH> 100644
--- a/lib/index.js
+++ b/lib/index.js
@@ -66,11 +66,10 @@ mnfy._js = function (string, options) {
 }
 
 mnfy._css = function (string, options) {
-  options = options || {
-    safe: true
-  }
+  options = options || {}
+  if (typeof options.safe !== 'boolean') options.safe = true
 
-  return _postcss()([_cssnano(options)]).process(string).then(function (result) {
+  return _postcss()([_cssnano()(options)]).process(string).then(function (result) {
     return {
       code: result.css,
     }
diff --git a/test/test.js b/test/test.js
index <HASH>..<HASH> 100644
--- a/test/test.js
+++ b/test/test.js
@@ -18,6 +18,12 @@ describe('Standalone', function () {
     })
   })
 
+  it('should minify CSS in safe mode by default', function () {
+    return mnfy.css('body { z-index: 1000; }').then(function (css) {
+      assert.equal(css.code, 'body{z-index:1000}')
+    })
+  })
+
   it('should minify HTML', function () {
     return mnfy.html('<html>    </html>').then(function (html) {
       assert.equal(html.code, '<html> </html>')
make sure cssnano is in safe mode by default

closes #3