diff --git a/tests/test_websocket.py b/tests/test_websocket.py
index acd7699..9d538db 100644
--- a/tests/test_websocket.py
+++ b/tests/test_websocket.py
@@ -343,3 +343,88 @@ class WebSocketServerTestCase(unittest.TestCase):
                                             socket.TCP_KEEPIDLE), keepidle)
         self.assertNotEqual(sock.getsockopt(socket.SOL_TCP,
                                             socket.TCP_KEEPINTVL), keepintvl)
+
+
+class HyBiEncodeDecodeTestCase(unittest.TestCase):
+    def test_decode_hybi_text(self):
+        buf = b'\x81\x85\x37\xfa\x21\x3d\x7f\x9f\x4d\x51\x58'
+        res = websocket.WebSocketRequestHandler.decode_hybi(buf)
+
+        self.assertEqual(res['fin'], 1)
+        self.assertEqual(res['opcode'], 0x1)
+        self.assertEqual(res['masked'], True)
+        self.assertEqual(res['length'], 5)
+        self.assertEqual(res['payload'], b'Hello')
+        self.assertEqual(res['left'], 0)
+
+    def test_decode_hybi_binary(self):
+        buf = b'\x82\x04\x01\x02\x03\x04'
+        res = websocket.WebSocketRequestHandler.decode_hybi(buf, strict=False)
+
+        self.assertEqual(res['fin'], 1)
+        self.assertEqual(res['opcode'], 0x2)
+        self.assertEqual(res['length'], 4)
+        self.assertEqual(res['payload'], b'\x01\x02\x03\x04')
+        self.assertEqual(res['left'], 0)
+
+    def test_decode_hybi_extended_16bit_binary(self):
+        data = (b'\x01\x02\x03\x04' * 65)  # len > 126 -- len == 260
+        buf = b'\x82\x7e\x01\x04' + data
+        res = websocket.WebSocketRequestHandler.decode_hybi(buf, strict=False)
+
+        self.assertEqual(res['fin'], 1)
+        self.assertEqual(res['opcode'], 0x2)
+        self.assertEqual(res['length'], 260)
+        self.assertEqual(res['payload'], data)
+        self.assertEqual(res['left'], 0)
+
+    def test_decode_hybi_extended_64bit_binary(self):
+        data = (b'\x01\x02\x03\x04' * 65)  # len > 126 -- len == 260
+        buf = b'\x82\x7f\x00\x00\x00\x00\x00\x00\x01\x04' + data
+        res = websocket.WebSocketRequestHandler.decode_hybi(buf, strict=False)
+
+        self.assertEqual(res['fin'], 1)
+        self.assertEqual(res['opcode'], 0x2)
+        self.assertEqual(res['length'], 260)
+        self.assertEqual(res['payload'], data)
+        self.assertEqual(res['left'], 0)
+
+    def test_decode_hybi_multi(self):
+        buf1 = b'\x01\x03\x48\x65\x6c'
+        buf2 = b'\x80\x02\x6c\x6f'
+
+        res1 = websocket.WebSocketRequestHandler.decode_hybi(buf1, strict=False)
+        self.assertEqual(res1['fin'], 0)
+        self.assertEqual(res1['opcode'], 0x1)
+        self.assertEqual(res1['length'], 3)
+        self.assertEqual(res1['payload'], b'Hel')
+        self.assertEqual(res1['left'], 0)
+
+        res2 = websocket.WebSocketRequestHandler.decode_hybi(buf2, strict=False)
+        self.assertEqual(res2['fin'], 1)
+        self.assertEqual(res2['opcode'], 0x0)
+        self.assertEqual(res2['length'], 2)
+        self.assertEqual(res2['payload'], b'lo')
+        self.assertEqual(res2['left'], 0)
+
+    def test_encode_hybi_basic(self):
+        res = websocket.WebSocketRequestHandler.encode_hybi(b'Hello', 0x1)
+        expected = (b'\x81\x05\x48\x65\x6c\x6c\x6f', 2, 0)
+
+        self.assertEqual(res, expected)
+
+    def test_strict_mode_refuses_unmasked_client_frames(self):
+        buf = b'\x81\x05\x48\x65\x6c\x6c\x6f'
+        self.assertRaises(websocket.WebSocketRequestHandler.CClose,
+                          websocket.WebSocketRequestHandler.decode_hybi,
+                          buf)
+
+    def test_no_strict_mode_accepts_unmasked_client_frames(self):
+        buf = b'\x81\x05\x48\x65\x6c\x6c\x6f'
+        res = websocket.WebSocketRequestHandler.decode_hybi(buf, strict=False)
+
+        self.assertEqual(res['fin'], 1)
+        self.assertEqual(res['opcode'], 0x1)
+        self.assertEqual(res['masked'], False)
+        self.assertEqual(res['length'], 5)
+        self.assertEqual(res['payload'], b'Hello')
diff --git a/websockify/websocket.py b/websockify/websocket.py
index 727413a..1cbf583 100644
--- a/websockify/websocket.py
+++ b/websockify/websocket.py
@@ -105,6 +105,7 @@ class WebSocketRequestHandler(SimpleHTTPRequestHandler):
         self.file_only = getattr(server, "file_only", False)
         self.traffic = getattr(server, "traffic", False)
         self.auto_pong = getattr(server, "auto_pong", False)
+        self.strict_mode = getattr(server, "strict_mode", True)
 
         self.logger = getattr(server, "logger", None)
         if self.logger is None:
@@ -177,7 +178,7 @@ class WebSocketRequestHandler(SimpleHTTPRequestHandler):
         return header + buf, len(header), 0
 
     @staticmethod
-    def decode_hybi(buf, base64=False, logger=None):
+    def decode_hybi(buf, base64=False, logger=None, strict=True):
         """ Decode HyBi style WebSocket packets.
         Returns:
             {'fin'          : 0_or_1,
@@ -243,6 +244,10 @@ class WebSocketRequestHandler(SimpleHTTPRequestHandler):
                                                   f['length'])
         else:
             logger.debug("Unmasked frame: %s" % repr(buf))
+
+            if strict:
+                raise WebSocketRequestHandler.CClose(1002, "The client sent an unmasked frame.")
+
             f['payload'] = buf[(f['hlen'] + f['masked'] * 4):full_len]
 
         if base64 and f['opcode'] in [1, 2]:
@@ -351,7 +356,8 @@ class WebSocketRequestHandler(SimpleHTTPRequestHandler):
 
         while buf:
             frame = self.decode_hybi(buf, base64=self.base64,
-                                     logger=self.logger)
+                                     logger=self.logger,
+                                     strict=self.strict_mode)
             #self.msg("Received buf: %s, frame: %s", repr(buf), frame)
 
             if frame['payload'] == None:
@@ -591,7 +597,7 @@ class WebSocketServer(object):
             file_only=False,
             run_once=False, timeout=0, idle_timeout=0, traffic=False,
             tcp_keepalive=True, tcp_keepcnt=None, tcp_keepidle=None,
-            tcp_keepintvl=None, auto_pong=False):
+            tcp_keepintvl=None, auto_pong=False, strict_mode=True):
 
         # settings
         self.RequestHandlerClass = RequestHandlerClass
@@ -606,6 +612,7 @@ class WebSocketServer(object):
         self.idle_timeout   = idle_timeout
         self.traffic        = traffic
         self.file_only      = file_only
+        self.strict_mode    = strict_mode
 
         self.launch_time    = time.time()
         self.ws_connection  = False