diff --git a/src/gateware/cxp_downconn.py b/src/gateware/cxp_downconn.py
index b7aa08a..d0d26ef 100644
--- a/src/gateware/cxp_downconn.py
+++ b/src/gateware/cxp_downconn.py
@@ -114,7 +114,7 @@ class CXP_DownConn_PHY(Module, AutoCSR):
                 self.sync.cxp_gtx_rx += [
                     fifo_out.sink.stb.eq(0),
                     # don't store idle word in fifo
-                    If(gtx.rx_ready & fifo_out.sink.ack & (gtx.decoders[0].d != 0xBC),
+                    If((gtx.rx_ready & fifo_out.sink.ack & (gtx.decoders[0].d != 0xBC) & (gtx.decoders[0].k != 1)),
                         fifo_out.sink.stb.eq(1),
                         fifo_out.sink.data[i*8:(i*8)+8].eq(gtx.decoders[i].d),
                         fifo_out.sink.k[i].eq(gtx.decoders[i].k),