diff --git a/src/eth/tb/taxi_eth_phy_10g/test_taxi_eth_phy_10g.py b/src/eth/tb/taxi_eth_phy_10g/test_taxi_eth_phy_10g.py
index 3f21279..58aeb21 100644
--- a/src/eth/tb/taxi_eth_phy_10g/test_taxi_eth_phy_10g.py
+++ b/src/eth/tb/taxi_eth_phy_10g/test_taxi_eth_phy_10g.py
@@ -51,6 +51,7 @@ class TB:
         cocotb.start_soon(Clock(dut.rx_clk, self.clk_period, units="ns").start())
 
         self.xgmii_source = XgmiiSource(dut.xgmii_txd, dut.xgmii_txc, dut.tx_clk, dut.tx_rst)
+        dut.xgmii_tx_valid.setimmediatevalue(1)
         self.xgmii_sink = XgmiiSink(dut.xgmii_rxd, dut.xgmii_rxc, dut.rx_clk, dut.rx_rst)
 
         self.serdes_source = BaseRSerdesSource(
diff --git a/src/eth/tb/taxi_eth_phy_1g_basex/test_taxi_eth_phy_1g_basex.py b/src/eth/tb/taxi_eth_phy_1g_basex/test_taxi_eth_phy_1g_basex.py
index 66dc045..bc5fc1e 100644
--- a/src/eth/tb/taxi_eth_phy_1g_basex/test_taxi_eth_phy_1g_basex.py
+++ b/src/eth/tb/taxi_eth_phy_1g_basex/test_taxi_eth_phy_1g_basex.py
@@ -52,6 +52,7 @@ class TB:
 
         self.gmii_source = GmiiSource(dut.gmii_txd, dut.gmii_tx_er, dut.gmii_tx_en,
             dut.tx_clk, dut.tx_rst)
+        dut.gmii_tx_valid.setimmediatevalue(1)
         self.gmii_sink = GmiiSink(dut.gmii_rxd, dut.gmii_rx_er, dut.gmii_rx_dv,
             dut.rx_clk, dut.rx_rst)