diff --git a/index.js b/index.js
index 0017aa3..b59d40b 100644
--- a/index.js
+++ b/index.js
@@ -29,7 +29,7 @@ module.exports = {
         tldHint      : '',
         httpHint     : ''
       };
-      options = _.defaults(options, defaults);
+      options = _.defaults({}, options, defaults);
 
       if (!_.isBoolean(options.isHTML)) {
         throw new Error('Invalid isHTML value');
diff --git a/test/runner.js b/test/runner.js
index 13cab79..1fab928 100755
--- a/test/runner.js
+++ b/test/runner.js
@@ -54,7 +54,8 @@ async function runEncodingHintTests() {
   try {
     await cld.detect(data.all[0].sample, { encodingHint: 'p' });
     assert.ok(false, 'Should not have detected');
-  } catch (err) {
+  }
+  catch (err) {
     assert.equal(err.message, 'Invalid encodingHint, see ENCODINGS');
   }
 }
@@ -123,7 +124,8 @@ async function runHttpHintTests() {
     let result;
     try {
       result = await cld.detect(item.sample, { httpHint: 'mi,en' });
-    } catch (err) {
+    }
+    catch (err) {
       assert.equal(err.message, 'Failed to identify language');
       return;
     }
@@ -135,11 +137,21 @@ async function runHttpHintTests() {
 async function runUnreliableTests() {
   try {
     await cld.detect('interaktive infografik \xc3\xbcber videospielkonsolen');
-  } catch (err) {
+  }
+  catch (err) {
     assert.equal(err.message, 'Failed to identify language');
   }
 }
 
+function runCallbackTests() {
+  cld.detect('This is a language recognition example', (err, result) => {
+    assert.equal(result.languages.length > 0, true);
+  });
+  cld.detect('This is a language recognition example', {isHTML:false}, (err, result) => {
+    assert.equal(result.languages.length > 0, true);
+  });
+}
+
 function runCrossCheckTests(detected) {
   // Confirm that we didn't detect languages that are not listed in DETECTED_LANGUAGES
   _.each(_.values(cld.DETECTED_LANGUAGES), function(val, key) {
@@ -159,5 +171,7 @@ function runCrossCheckTests(detected) {
   await runTldHintTests();
   await runHttpHintTests();
   await runUnreliableTests();
+
+  runCallbackTests();
   runCrossCheckTests(detected);
 })();