diff --git a/tb/test_eth_mac_10g_rx.py b/tb/test_eth_mac_10g_rx.py
index 55d32f45..f792cc21 100755
--- a/tb/test_eth_mac_10g_rx.py
+++ b/tb/test_eth_mac_10g_rx.py
@@ -341,18 +341,56 @@ def bench():
 
                 source.send(b'\x55\x55\x55\x55\x55\x55\x55\xD5'+bytearray(axis_frame))
 
-            yield clk.posedge
-            yield clk.posedge
+            for i in range(10):
+                yield sink.wait()
+                rx_frame = sink.recv()
 
-            while xgmii_rxc != 0xff or output_axis_tvalid or not source.empty():
-                yield clk.posedge
+                eth_frame = eth_ep.EthFrame()
+                eth_frame.parse_axis(rx_frame)
+                eth_frame.update_fcs()
 
-            yield clk.posedge
-            yield clk.posedge
-            yield clk.posedge
+                assert eth_frame == test_frame
 
             yield delay(100)
 
+        yield clk.posedge
+        print("test 6: Ensure 0xfb in FCS in lane 4 is not detected as start code in lane 0")
+        current_test.next = 6
+
+        test_frame = eth_ep.EthFrame()
+        test_frame.eth_dest_mac = 0xDAD1D2D3D4D5
+        test_frame.eth_src_mac = 0x5A5152535455
+        test_frame.eth_type = 0x806f
+        test_frame.payload = bytearray(range(60))
+        test_frame.update_fcs()
+
+        axis_frame = test_frame.build_axis_fcs()
+
+        error_bad_frame_asserted.next = 0
+        error_bad_fcs_asserted.next = 0
+
+        xgmii_frame = xgmii_ep.XGMIIFrame(b'\x55\x55\x55\x55\x55\x55\x55\xD5'+bytearray(axis_frame))
+
+        source.send(xgmii_frame)
+
+        yield sink.wait()
+        rx_frame = sink.recv()
+
+        assert not error_bad_frame_asserted
+        assert not error_bad_fcs_asserted
+
+        assert not rx_frame.last_cycle_user
+
+        eth_frame = eth_ep.EthFrame()
+        eth_frame.parse_axis(rx_frame)
+        eth_frame.update_fcs()
+
+        assert eth_frame == test_frame
+
+        assert sink.empty()
+
+        yield delay(100)
+
         raise StopSimulation
 
     return instances()
diff --git a/tb/test_eth_mac_10g_tx.py b/tb/test_eth_mac_10g_tx.py
index 1b6ba623..0bcf42df 100755
--- a/tb/test_eth_mac_10g_tx.py
+++ b/tb/test_eth_mac_10g_tx.py
@@ -309,15 +309,21 @@ def bench():
 
                 source.send(axis_frame)
 
-            yield clk.posedge
-            yield clk.posedge
+            for i in range(10):
+                yield sink.wait()
+                rx_frame = sink.recv()
 
-            while xgmii_txc != 0xff or input_axis_tvalid:
-                yield clk.posedge
+                assert rx_frame.data[0:8] == bytearray(b'\x55\x55\x55\x55\x55\x55\x55\xD5')
 
-            yield clk.posedge
-            yield clk.posedge
-            yield clk.posedge
+                eth_frame = eth_ep.EthFrame()
+                eth_frame.parse_axis_fcs(rx_frame.data[8:])
+
+                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
 
             yield delay(100)