diff --git a/index.js b/index.js
index 5628b80..4319911 100644
--- a/index.js
+++ b/index.js
@@ -35,7 +35,7 @@ module.exports = function (args, opts) {
         setKey(argv, key.split('.'), value);
         
         (aliases[key] || []).forEach(function (x) {
-            argv[x] = argv[key];
+            setKey(argv, x.split('.'), value);
         });
     }
     
@@ -129,17 +129,28 @@ module.exports = function (args, opts) {
     }
     
     Object.keys(defaults).forEach(function (key) {
-        if (!(key in argv)) {
-            argv[key] = defaults[key];
-            if (key in aliases) {
-                argv[aliases[key]] = defaults[key];
-            }
+        if (!hasKey(argv, key.split('.'))) {
+            setKey(argv, key.split('.'), defaults[key]);
+            
+            (aliases[key] || []).forEach(function (x) {
+                setKey(argv, x.split('.'), defaults[key]);
+            });
         }
     });
     
     return argv;
 };
 
+function hasKey (obj, keys) {
+    var o = obj;
+    keys.slice(0,-1).forEach(function (key) {
+        o = (o[key] || {});
+    });
+
+    var key = keys[keys.length - 1];
+    return key in o;
+}
+
 function setKey (obj, keys, value) {
     var o = obj;
     keys.slice(0,-1).forEach(function (key) {
diff --git a/test/dotted.js b/test/dotted.js
new file mode 100644
index 0000000..ef0ae34
--- /dev/null
+++ b/test/dotted.js
@@ -0,0 +1,16 @@
+var parse = require('../');
+var test = require('tape');
+
+test('dotted alias', function (t) {
+    var argv = parse(['--a.b', '22'], {default: {'a.b': 11}, alias: {'a.b': 'aa.bb'}});
+    t.equal(argv.a.b, 22);
+    t.equal(argv.aa.bb, 22);
+    t.end();
+});
+
+test('dotted default', function (t) {
+    var argv = parse('', {default: {'a.b': 11}, alias: {'a.b': 'aa.bb'}});
+    t.equal(argv.a.b, 11);
+    t.equal(argv.aa.bb, 11);
+    t.end();
+});