diff --git a/tests/hwsim/radius_das.py b/tests/hwsim/radius_das.py
index b22f02cbf..1dd0c5e5b 100644
--- a/tests/hwsim/radius_das.py
+++ b/tests/hwsim/radius_das.py
@@ -27,3 +27,20 @@ class DisconnectPacket(pyrad.packet.Packet):
         self.authenticator = hashlib.md5(header[0:4] + 16 * b'\x00' + attr
             + self.secret).digest()
         return header + self.authenticator + attr
+
+class CoAPacket(pyrad.packet.Packet):
+    def __init__(self, code=pyrad.packet.CoARequest, id=None,
+                 secret=None, authenticator=None, **attributes):
+        pyrad.packet.Packet.__init__(self, code, id, secret, authenticator,
+                                     **attributes)
+
+    def RequestPacket(self):
+        attr = self._PktEncodeAttributes()
+
+        if self.id is None:
+            self.id = random.randrange(0, 256)
+
+        header = struct.pack('!BBH', self.code, self.id, (20 + len(attr)))
+        self.authenticator = hashlib.md5(header[0:4] + 16 * b'\x00' + attr
+            + self.secret).digest()
+        return header + self.authenticator + attr
diff --git a/tests/hwsim/test_radius.py b/tests/hwsim/test_radius.py
index e177549e8..e68e43c30 100644
--- a/tests/hwsim/test_radius.py
+++ b/tests/hwsim/test_radius.py
@@ -307,3 +307,46 @@ def test_radius_das_disconnect(dev, apdev):
     ev = dev[0].wait_event(["CTRL-EVENT-CONNECTED"])
     if ev is None:
         raise Exception("Timeout while waiting for re-connection")
+
+def test_radius_das_coa(dev, apdev):
+    """RADIUS Dynamic Authorization Extensions - CoA"""
+    try:
+        import pyrad.client
+        import pyrad.packet
+        import pyrad.dictionary
+        import radius_das
+    except ImportError:
+        return "skip"
+
+    params = hostapd.wpa2_eap_params(ssid="radius-das")
+    params['radius_das_port'] = "3799"
+    params['radius_das_client'] = "127.0.0.1 secret"
+    params['radius_das_require_event_timestamp'] = "1"
+    hapd = hostapd.add_ap(apdev[0]['ifname'], params)
+    connect(dev[0], "radius-das")
+    addr = dev[0].p2p_interface_addr()
+    sta = hapd.get_sta(addr)
+    id = sta['dot1xAuthSessionId']
+
+    dict = pyrad.dictionary.Dictionary("dictionary.radius")
+
+    srv = pyrad.client.Client(server="127.0.0.1", acctport=3799,
+                              secret="secret", dict=dict)
+    srv.retries = 1
+    srv.timeout = 1
+
+    # hostapd does not currently support CoA-Request, so NAK is expected
+    logger.info("CoA-Request with matching Acct-Session-Id")
+    req = radius_das.CoAPacket(dict=dict, secret="secret",
+                               Acct_Session_Id=id,
+                               Event_Timestamp=int(time.time()))
+    reply = srv.SendPacket(req)
+    logger.debug("RADIUS response from hostapd")
+    for i in reply.keys():
+        logger.debug("%s: %s" % (i, reply[i]))
+    if reply.code != pyrad.packet.CoANAK:
+        raise Exception("Unexpected response code")
+    if 'Error-Cause' not in reply:
+        raise Exception("Missing Error-Cause")
+    if reply['Error-Cause'][0] != 405:
+        raise Exception("Unexpected Error-Cause: {}".format(reply['Error-Cause']))