diff --git a/liteeth/common.py b/liteeth/common.py
index e68e4c498..ddb14e2df 100644
--- a/liteeth/common.py
+++ b/liteeth/common.py
@@ -77,6 +77,13 @@ udp_header = {
 	"checksum":					HField( 6,  0, 16)
 }
 
+def reverse_bytes(v):
+	n = math.ceil(flen(v)//8)
+	r = []
+	for i in reversed(range(n)):
+		r.append(v[i*8:min((i+1)*8, flen(v))])
+	return Cat(iter(r))
+
 # layouts
 def _layout_from_header(header):
 	_layout = []
diff --git a/liteeth/generic/depacketizer.py b/liteeth/generic/depacketizer.py
index e4525a0c5..39d111362 100644
--- a/liteeth/generic/depacketizer.py
+++ b/liteeth/generic/depacketizer.py
@@ -5,7 +5,7 @@ def _decode_header(h_dict, h_signal, obj):
 	for k, v in sorted(h_dict.items()):
 		start = v.byte*8+v.offset
 		end = start+v.width
-		r.append(getattr(obj, k).eq(h_signal[start:end]))
+		r.append(getattr(obj, k).eq(reverse_bytes(h_signal[start:end])))
 	return r
 
 class LiteEthDepacketizer(Module):
@@ -18,6 +18,12 @@ class LiteEthDepacketizer(Module):
 		counter = Counter(max=header_length)
 		self.submodules += counter
 
+		self.sync += [
+			If(shift,
+				header.eq(Cat(header[8:], sink.data))
+			)
+		]
+
 		fsm = FSM(reset_state="IDLE")
 		self.submodules += fsm
 
diff --git a/liteeth/generic/packetizer.py b/liteeth/generic/packetizer.py
index 2aa161ef4..4fb788f16 100644
--- a/liteeth/generic/packetizer.py
+++ b/liteeth/generic/packetizer.py
@@ -1,12 +1,4 @@
 from liteeth.common import *
-import math
-
-def reverse_bytes(v):
-	n = math.ceil(flen(v)//8)
-	r = []
-	for i in reversed(range(n)):
-		r.append(v[i*8:min((i+1)*8, flen(v))])
-	return Cat(iter(r))
 
 def _encode_header(h_dict, h_signal, obj):
 	r = []
diff --git a/liteeth/test/arp_tb.py b/liteeth/test/arp_tb.py
index b4629c893..e11a11011 100644
--- a/liteeth/test/arp_tb.py
+++ b/liteeth/test/arp_tb.py
@@ -51,4 +51,4 @@ class TB(Module):
 		selfp.arp.table.request.stb = 1
 
 if __name__ == "__main__":
-	run_simulation(TB(), ncycles=256, vcd_name="my.vcd", keep_files=True)
+	run_simulation(TB(), ncycles=1024, vcd_name="my.vcd", keep_files=True)