diff --git a/tb/test_axis_eth_fcs_insert.py b/tb/test_axis_eth_fcs_insert.py
index df6ef3d8c..be271d576 100755
--- a/tb/test_axis_eth_fcs_insert.py
+++ b/tb/test_axis_eth_fcs_insert.py
@@ -227,7 +227,7 @@ def bench():
                 print(hex(eth_frame.eth_fcs))
                 print(hex(eth_frame.calc_fcs()))
 
-                assert len(eth_frame.payload.data) == max(payload_len, 46)
+                assert eth_frame.payload.data == test_frame.payload.data
                 assert eth_frame.eth_fcs == eth_frame.calc_fcs()
                 assert eth_frame.eth_dest_mac == test_frame.eth_dest_mac
                 assert eth_frame.eth_src_mac == test_frame.eth_src_mac
@@ -280,7 +280,7 @@ def bench():
                 print(hex(eth_frame.eth_fcs))
                 print(hex(eth_frame.calc_fcs()))
 
-                assert len(eth_frame.payload.data) == max(payload_len, 46)
+                assert eth_frame.payload.data == test_frame1.payload.data
                 assert eth_frame.eth_fcs == eth_frame.calc_fcs()
                 assert eth_frame.eth_dest_mac == test_frame1.eth_dest_mac
                 assert eth_frame.eth_src_mac == test_frame1.eth_src_mac
@@ -297,7 +297,7 @@ def bench():
                 print(hex(eth_frame.eth_fcs))
                 print(hex(eth_frame.calc_fcs()))
 
-                assert len(eth_frame.payload.data) == max(payload_len, 46)
+                assert eth_frame.payload.data == test_frame2.payload.data
                 assert eth_frame.eth_fcs == eth_frame.calc_fcs()
                 assert eth_frame.eth_dest_mac == test_frame2.eth_dest_mac
                 assert eth_frame.eth_src_mac == test_frame2.eth_src_mac
@@ -358,7 +358,7 @@ def bench():
                 print(hex(eth_frame.eth_fcs))
                 print(hex(eth_frame.calc_fcs()))
 
-                assert len(eth_frame.payload.data) == max(payload_len, 46)
+                assert eth_frame.payload.data == test_frame2.payload.data
                 assert eth_frame.eth_fcs == eth_frame.calc_fcs()
                 assert eth_frame.eth_dest_mac == test_frame2.eth_dest_mac
                 assert eth_frame.eth_src_mac == test_frame2.eth_src_mac
diff --git a/tb/test_axis_eth_fcs_insert.v b/tb/test_axis_eth_fcs_insert.v
index 8cf67d99c..39f966fd3 100644
--- a/tb/test_axis_eth_fcs_insert.v
+++ b/tb/test_axis_eth_fcs_insert.v
@@ -32,7 +32,7 @@ THE SOFTWARE.
 module test_axis_eth_fcs_insert;
 
 // Parameters
-parameter ENABLE_PADDING = 1;
+parameter ENABLE_PADDING = 0;
 parameter MIN_FRAME_LENGTH = 64;
 
 // Inputs
diff --git a/tb/test_axis_eth_fcs_insert_pad.py b/tb/test_axis_eth_fcs_insert_pad.py
new file mode 100755
index 000000000..6c972b43d
--- /dev/null
+++ b/tb/test_axis_eth_fcs_insert_pad.py
@@ -0,0 +1,382 @@
+#!/usr/bin/env python2
+"""
+
+Copyright (c) 2015 Alex Forencich
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.
+
+"""
+
+from myhdl import *
+import os
+from Queue import Queue
+
+import axis_ep
+import eth_ep
+
+module = 'axis_eth_fcs_insert'
+
+srcs = []
+
+srcs.append("../rtl/%s.v" % module)
+srcs.append("../rtl/eth_crc_8.v")
+srcs.append("test_%s_pad.v" % module)
+
+src = ' '.join(srcs)
+
+build_cmd = "iverilog -o test_%s.vvp %s" % (module, src)
+
+def dut_axis_eth_fcs_insert(clk,
+                            rst,
+                            current_test,
+                            
+                            input_axis_tdata,
+                            input_axis_tvalid,
+                            input_axis_tready,
+                            input_axis_tlast,
+                            input_axis_tuser,
+                            
+                            output_axis_tdata,
+                            output_axis_tvalid,
+                            output_axis_tready,
+                            output_axis_tlast,
+                            output_axis_tuser,
+
+                            busy):
+
+    if os.system(build_cmd):
+        raise Exception("Error running build command")
+    return Cosimulation("vvp -m myhdl test_%s.vvp -lxt2" % module,
+                clk=clk,
+                rst=rst,
+                current_test=current_test,
+
+                input_axis_tdata=input_axis_tdata,
+                input_axis_tvalid=input_axis_tvalid,
+                input_axis_tready=input_axis_tready,
+                input_axis_tlast=input_axis_tlast,
+                input_axis_tuser=input_axis_tuser,
+
+                output_axis_tdata=output_axis_tdata,
+                output_axis_tvalid=output_axis_tvalid,
+                output_axis_tready=output_axis_tready,
+                output_axis_tlast=output_axis_tlast,
+                output_axis_tuser=output_axis_tuser,
+
+                busy=busy)
+
+def bench():
+
+    # Parameters
+    ENABLE_PADDING = 1
+    MIN_FRAME_LENGTH = 64
+
+    # Inputs
+    clk = Signal(bool(0))
+    rst = Signal(bool(0))
+    current_test = Signal(intbv(0)[8:])
+
+    input_axis_tdata = Signal(intbv(0)[8:])
+    input_axis_tvalid = Signal(bool(0))
+    input_axis_tlast = Signal(bool(0))
+    input_axis_tuser = Signal(bool(0))
+    output_axis_tready = Signal(bool(0))
+
+    # Outputs
+    input_axis_tready = Signal(bool(0))
+    output_axis_tdata = Signal(intbv(0)[8:])
+    output_axis_tvalid = Signal(bool(0))
+    output_axis_tlast = Signal(bool(0))
+    output_axis_tuser = Signal(bool(0))
+    busy = Signal(bool(0))
+
+    # sources and sinks
+    source_queue = Queue()
+    source_pause = Signal(bool(0))
+    sink_queue = Queue()
+    sink_pause = Signal(bool(0))
+
+    source = axis_ep.AXIStreamSource(clk,
+                                     rst,
+                                     tdata=input_axis_tdata,
+                                     tvalid=input_axis_tvalid,
+                                     tready=input_axis_tready,
+                                     tlast=input_axis_tlast,
+                                     tuser=input_axis_tuser,
+                                     fifo=source_queue,
+                                     pause=source_pause,
+                                     name='source')
+
+    sink = axis_ep.AXIStreamSink(clk,
+                                rst,
+                                tdata=output_axis_tdata,
+                                tvalid=output_axis_tvalid,
+                                tready=output_axis_tready,
+                                tlast=output_axis_tlast,
+                                tuser=output_axis_tuser,
+                                fifo=sink_queue,
+                                pause=sink_pause,
+                                name='sink')
+
+    # DUT
+    dut = dut_axis_eth_fcs_insert(clk,
+                                  rst,
+                                  current_test,
+
+                                  input_axis_tdata,
+                                  input_axis_tvalid,
+                                  input_axis_tready,
+                                  input_axis_tlast,
+                                  input_axis_tuser,
+
+                                  output_axis_tdata,
+                                  output_axis_tvalid,
+                                  output_axis_tready,
+                                  output_axis_tlast,
+                                  output_axis_tuser,
+
+                                  busy)
+
+    @always(delay(4))
+    def clkgen():
+        clk.next = not clk
+
+    def wait_normal():
+        while input_axis_tvalid or output_axis_tvalid:
+            yield clk.posedge
+
+    def wait_pause_source():
+        while input_axis_tvalid or output_axis_tvalid:
+            source_pause.next = True
+            yield clk.posedge
+            yield clk.posedge
+            yield clk.posedge
+            source_pause.next = False
+            yield clk.posedge
+
+    def wait_pause_sink():
+        while input_axis_tvalid or output_axis_tvalid:
+            sink_pause.next = True
+            yield clk.posedge
+            yield clk.posedge
+            yield clk.posedge
+            sink_pause.next = False
+            yield clk.posedge
+
+    @instance
+    def check():
+        yield delay(100)
+        yield clk.posedge
+        rst.next = 1
+        yield clk.posedge
+        rst.next = 0
+        yield clk.posedge
+        yield delay(100)
+        yield clk.posedge
+
+        # testbench stimulus
+
+        for payload_len in list(range(1,18))+list(range(64,82)):
+            yield clk.posedge
+            print("test 1: test packet, length %d" % payload_len)
+            current_test.next = 1
+
+            test_frame = eth_ep.EthFrame()
+            test_frame.eth_dest_mac = 0xDAD1D2D3D4D5
+            test_frame.eth_src_mac = 0x5A5152535455
+            test_frame.eth_type = 0x8000
+            test_frame.payload = bytearray(range(payload_len))
+            test_frame.update_fcs()
+
+            axis_frame = test_frame.build_axis()
+
+            for wait in wait_normal, wait_pause_source, wait_pause_sink:
+                source_queue.put(axis_frame)
+                yield clk.posedge
+                yield clk.posedge
+
+                yield wait()
+
+                yield clk.posedge
+                yield clk.posedge
+                yield clk.posedge
+
+                rx_frame = None
+                if not sink_queue.empty():
+                    rx_frame = sink_queue.get()
+
+                eth_frame = eth_ep.EthFrame()
+                eth_frame.parse_axis_fcs(rx_frame)
+
+                print(hex(eth_frame.eth_fcs))
+                print(hex(eth_frame.calc_fcs()))
+
+                assert len(eth_frame.payload.data) == max(payload_len, 46)
+                assert eth_frame.eth_fcs == eth_frame.calc_fcs()
+                assert eth_frame.eth_dest_mac == test_frame.eth_dest_mac
+                assert eth_frame.eth_src_mac == test_frame.eth_src_mac
+                assert eth_frame.eth_type == test_frame.eth_type
+                assert eth_frame.payload.data.index(test_frame.payload.data) == 0
+
+                assert sink_queue.empty()
+
+                yield delay(100)
+
+            yield clk.posedge
+            print("test 2: back-to-back packets, length %d" % payload_len)
+            current_test.next = 2
+
+            test_frame1 = eth_ep.EthFrame()
+            test_frame1.eth_dest_mac = 0xDAD1D2D3D4D5
+            test_frame1.eth_src_mac = 0x5A5152535455
+            test_frame1.eth_type = 0x8000
+            test_frame1.payload = bytearray(range(payload_len))
+            test_frame1.update_fcs()
+            test_frame2 = eth_ep.EthFrame()
+            test_frame2.eth_dest_mac = 0xDAD1D2D3D4D5
+            test_frame2.eth_src_mac = 0x5A5152535455
+            test_frame2.eth_type = 0x8000
+            test_frame2.payload = bytearray(range(payload_len))
+            test_frame2.update_fcs()
+
+            axis_frame1 = test_frame1.build_axis()
+            axis_frame2 = test_frame2.build_axis()
+
+            for wait in wait_normal, wait_pause_source, wait_pause_sink:
+                source_queue.put(axis_frame1)
+                source_queue.put(axis_frame2)
+                yield clk.posedge
+                yield clk.posedge
+
+                yield wait()
+
+                yield clk.posedge
+                yield clk.posedge
+                yield clk.posedge
+
+                rx_frame = None
+                if not sink_queue.empty():
+                    rx_frame = sink_queue.get()
+
+                eth_frame = eth_ep.EthFrame()
+                eth_frame.parse_axis_fcs(rx_frame)
+
+                print(hex(eth_frame.eth_fcs))
+                print(hex(eth_frame.calc_fcs()))
+
+                assert len(eth_frame.payload.data) == max(payload_len, 46)
+                assert eth_frame.eth_fcs == eth_frame.calc_fcs()
+                assert eth_frame.eth_dest_mac == test_frame1.eth_dest_mac
+                assert eth_frame.eth_src_mac == test_frame1.eth_src_mac
+                assert eth_frame.eth_type == test_frame1.eth_type
+                assert eth_frame.payload.data.index(test_frame1.payload.data) == 0
+
+                rx_frame = None
+                if not sink_queue.empty():
+                    rx_frame = sink_queue.get()
+
+                eth_frame = eth_ep.EthFrame()
+                eth_frame.parse_axis_fcs(rx_frame)
+
+                print(hex(eth_frame.eth_fcs))
+                print(hex(eth_frame.calc_fcs()))
+
+                assert len(eth_frame.payload.data) == max(payload_len, 46)
+                assert eth_frame.eth_fcs == eth_frame.calc_fcs()
+                assert eth_frame.eth_dest_mac == test_frame2.eth_dest_mac
+                assert eth_frame.eth_src_mac == test_frame2.eth_src_mac
+                assert eth_frame.eth_type == test_frame2.eth_type
+                assert eth_frame.payload.data.index(test_frame2.payload.data) == 0
+
+                assert sink_queue.empty()
+
+                yield delay(100)
+
+            yield clk.posedge
+            print("test 3: tuser assert, length %d" % payload_len)
+            current_test.next = 3
+
+            test_frame1 = eth_ep.EthFrame()
+            test_frame1.eth_dest_mac = 0xDAD1D2D3D4D5
+            test_frame1.eth_src_mac = 0x5A5152535455
+            test_frame1.eth_type = 0x8000
+            test_frame1.payload = bytearray(range(payload_len))
+            test_frame1.update_fcs()
+            test_frame2 = eth_ep.EthFrame()
+            test_frame2.eth_dest_mac = 0xDAD1D2D3D4D5
+            test_frame2.eth_src_mac = 0x5A5152535455
+            test_frame2.eth_type = 0x8000
+            test_frame2.payload = bytearray(range(payload_len))
+            test_frame2.update_fcs()
+
+            axis_frame1 = test_frame1.build_axis()
+            axis_frame2 = test_frame2.build_axis()
+
+            axis_frame1.user = 1
+
+            for wait in wait_normal, wait_pause_source, wait_pause_sink:
+                source_queue.put(axis_frame1)
+                source_queue.put(axis_frame2)
+                yield clk.posedge
+                yield clk.posedge
+
+                yield wait()
+
+                yield clk.posedge
+                yield clk.posedge
+                yield clk.posedge
+
+                rx_frame = None
+                if not sink_queue.empty():
+                    rx_frame = sink_queue.get()
+
+                assert rx_frame.user[-1]
+
+                rx_frame = None
+                if not sink_queue.empty():
+                    rx_frame = sink_queue.get()
+
+                eth_frame = eth_ep.EthFrame()
+                eth_frame.parse_axis_fcs(rx_frame)
+
+                print(hex(eth_frame.eth_fcs))
+                print(hex(eth_frame.calc_fcs()))
+
+                assert len(eth_frame.payload.data) == max(payload_len, 46)
+                assert eth_frame.eth_fcs == eth_frame.calc_fcs()
+                assert eth_frame.eth_dest_mac == test_frame2.eth_dest_mac
+                assert eth_frame.eth_src_mac == test_frame2.eth_src_mac
+                assert eth_frame.eth_type == test_frame2.eth_type
+                assert eth_frame.payload.data.index(test_frame2.payload.data) == 0
+
+                assert sink_queue.empty()
+
+                yield delay(100)
+
+        raise StopSimulation
+
+    return dut, source, sink, clkgen, check
+
+def test_bench():
+    sim = Simulation(bench())
+    sim.run()
+
+if __name__ == '__main__':
+    print("Running test...")
+    test_bench()
diff --git a/tb/test_axis_eth_fcs_insert_pad.v b/tb/test_axis_eth_fcs_insert_pad.v
new file mode 100644
index 000000000..5464d7c99
--- /dev/null
+++ b/tb/test_axis_eth_fcs_insert_pad.v
@@ -0,0 +1,99 @@
+/*
+
+Copyright (c) 2015 Alex Forencich
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.
+
+*/
+
+// Language: Verilog 2001
+
+`timescale 1ns / 1ps
+
+/*
+ * Testbench for axis_eth_fcs_insert
+ */
+module test_axis_eth_fcs_insert_pad;
+
+// Parameters
+parameter ENABLE_PADDING = 1;
+parameter MIN_FRAME_LENGTH = 64;
+
+// Inputs
+reg clk = 0;
+reg rst = 0;
+reg [7:0] current_test = 0;
+
+reg [7:0] input_axis_tdata = 0;
+reg input_axis_tvalid = 0;
+reg input_axis_tlast = 0;
+reg input_axis_tuser = 0;
+reg output_axis_tready = 0;
+
+// Outputs
+wire input_axis_tready;
+wire [7:0] output_axis_tdata;
+wire output_axis_tvalid;
+wire output_axis_tlast;
+wire output_axis_tuser;
+wire busy;
+
+initial begin
+    // myhdl integration
+    $from_myhdl(clk,
+                rst,
+                current_test,
+                input_axis_tdata,
+                input_axis_tvalid,
+                input_axis_tlast,
+                input_axis_tuser,
+                output_axis_tready);
+    $to_myhdl(input_axis_tready,
+              output_axis_tdata,
+              output_axis_tvalid,
+              output_axis_tlast,
+              output_axis_tuser,
+              busy);
+
+    // dump file
+    $dumpfile("test_axis_eth_fcs_insert_pad.lxt");
+    $dumpvars(0, test_axis_eth_fcs_insert_pad);
+end
+
+axis_eth_fcs_insert #(
+    .ENABLE_PADDING(ENABLE_PADDING),
+    .MIN_FRAME_LENGTH(MIN_FRAME_LENGTH)
+)
+UUT (
+    .clk(clk),
+    .rst(rst),
+    .input_axis_tdata(input_axis_tdata),
+    .input_axis_tvalid(input_axis_tvalid),
+    .input_axis_tready(input_axis_tready),
+    .input_axis_tlast(input_axis_tlast),
+    .input_axis_tuser(input_axis_tuser),
+    .output_axis_tdata(output_axis_tdata),
+    .output_axis_tvalid(output_axis_tvalid),
+    .output_axis_tready(output_axis_tready),
+    .output_axis_tlast(output_axis_tlast),
+    .output_axis_tuser(output_axis_tuser),
+    .busy(busy)
+);
+
+endmodule