diff --git a/test/test_packet.py b/test/test_packet.py
new file mode 100644
index 000000000..0fe6bf228
--- /dev/null
+++ b/test/test_packet.py
@@ -0,0 +1,107 @@
+# This file is Copyright (c) 2019 Florent Kermarrec <florent@enjoy-digital.fr>
+# License: BSD
+
+import unittest
+import random
+
+from migen import *
+
+from litex.soc.interconnect.stream import *
+from litex.soc.interconnect.packet import *
+
+packet_header_length = 31
+packet_header_fields = {
+    "field_8b"  : HeaderField(0,  0,   8),
+    "field_16b" : HeaderField(1,  0,  16),
+    "field_32b" : HeaderField(3,  0,  32),
+    "field_64b" : HeaderField(7,  0,  64),
+    "field_128b": HeaderField(15, 0, 128),
+}
+packet_header = Header(
+    fields           = packet_header_fields,
+    length           = packet_header_length,
+    swap_field_bytes = True)
+
+def packet_description(dw):
+    param_layout = packet_header.get_layout()
+    payload_layout = [("data", dw)]
+    return EndpointDescription(payload_layout, param_layout)
+
+def raw_description(dw):
+    payload_layout = [("data", dw)]
+    return EndpointDescription(payload_layout)
+
+class Packet:
+    def __init__(self, header, datas):
+        self.header = header
+        self.datas  = datas
+
+
+class TestPacket(unittest.TestCase):
+    def test_loopback(self):
+        prng = random.Random(42)
+        # Prepare packets
+        npackets = 8
+        packets  = []
+        for n in range(npackets):
+            header               = {}
+            header["field_8b"]   = prng.randrange(2**8)
+            header["field_16b"]  = prng.randrange(2**16)
+            header["field_32b"]  = prng.randrange(2**32)
+            header["field_64b"]  = prng.randrange(2**64)
+            header["field_128b"] = prng.randrange(2**128)
+            datas = [prng.randrange(2**8) for _ in range(prng.randrange(2**7))]
+            packets.append(Packet(header, datas))
+
+        def generator(dut):
+            # Send packets
+            for packet in packets:
+                yield dut.sink.field_8b.eq(packet.header["field_8b"])
+                yield dut.sink.field_16b.eq(packet.header["field_16b"])
+                yield dut.sink.field_32b.eq(packet.header["field_32b"])
+                yield dut.sink.field_64b.eq(packet.header["field_64b"])
+                yield dut.sink.field_128b.eq(packet.header["field_128b"])
+                yield
+                for n, data in enumerate(packet.datas):
+                    yield dut.sink.valid.eq(1)
+                    yield dut.sink.last.eq(n == (len(packet.datas) - 1))
+                    yield dut.sink.data.eq(data)
+                    yield
+                    while (yield dut.sink.ready) == 0:
+                        yield
+                    dut.sink.valid.eq(0)
+
+        def checker(dut):
+            dut.header_errors = 0
+            dut.data_errors   = 0
+            dut.last_errors   = 0
+            # Receive and check packets
+            yield dut.source.ready.eq(1)
+            for packet in packets:
+                for n, data in enumerate(packet.datas):
+                    while (yield dut.source.valid) == 0:
+                        yield
+                    for field in ["field_8b", "field_16b", "field_32b", "field_64b", "field_128b"]:
+                        if (yield getattr(dut.source, field)) != packet.header[field]:
+                            dut.header_errors += 1
+                    #print("{:02x} vs {:02x}".format((yield dut.source.data), data))
+                    if ((yield dut.source.data) != data):
+                        dut.data_errors += 1
+                    if ((yield dut.source.last) != (n == (len(packet.datas) - 1))):
+                        dut.last_errors += 1
+                    yield
+            yield
+
+        class DUT(Module):
+            def __init__(self):
+                packetizer   = Packetizer(packet_description(8), raw_description(8), packet_header)
+                depacketizer = Depacketizer(raw_description(8), packet_description(8), packet_header)
+                self.submodules += packetizer, depacketizer
+                self.comb += packetizer.source.connect(depacketizer.sink)
+                self.sink, self.source = packetizer.sink, depacketizer.source
+
+        dut = DUT()
+        run_simulation(dut, [generator(dut), checker(dut)])
+        self.assertEqual(dut.header_errors, 0)
+        self.assertEqual(dut.data_errors,   0)
+        self.assertEqual(dut.last_errors,   0)