diff --git a/ryu/lib/packet/udp.py b/ryu/lib/packet/udp.py
index e3bf5e5f..a960886d 100644
--- a/ryu/lib/packet/udp.py
+++ b/ryu/lib/packet/udp.py
@@ -41,7 +41,7 @@ class udp(packet_base.PacketBase):
     _PACK_STR = '!HHHH'
     _MIN_LEN = struct.calcsize(_PACK_STR)
 
-    def __init__(self, src_port, dst_port, total_length=0, csum=0):
+    def __init__(self, src_port=0, dst_port=0, total_length=0, csum=0):
         super(udp, self).__init__()
         self.src_port = src_port
         self.dst_port = dst_port
diff --git a/ryu/tests/unit/packet/test_udp.py b/ryu/tests/unit/packet/test_udp.py
index 64187436..40da616b 100644
--- a/ryu/tests/unit/packet/test_udp.py
+++ b/ryu/tests/unit/packet/test_udp.py
@@ -94,3 +94,13 @@ class Test_udp(unittest.TestCase):
     def test_malformed_udp(self):
         m_short_buf = self.buf[1:udp._MIN_LEN]
         udp.parser(m_short_buf)
+
+    def test_default_args(self):
+        prev = ipv4(proto=inet.IPPROTO_UDP)
+        u = udp()
+        buf = u.serialize(bytearray(), prev)
+        res = struct.unpack(udp._PACK_STR, buf)
+
+        eq_(res[0], 0)
+        eq_(res[1], 0)
+        eq_(res[2], udp._MIN_LEN)