diff --git a/setup.py b/setup.py
index 89e2caec..b4511fa3 100755
--- a/setup.py
+++ b/setup.py
@@ -60,6 +60,10 @@
         ],
     'test_suite': 'tests',
     'provides': ['dns'],
+    'extras_require': {
+        'IDNA': ['idna>=2.1'],
+        'DNSSEC': ['pycrypto>=2.6.1', 'ecdsa>=0.13'],
+        },
     }
 
 setup(**kwargs)