diff --git a/libraries/io/tr_10GbE/src/vhdl/tr_10GbE.vhd b/libraries/io/tr_10GbE/src/vhdl/tr_10GbE.vhd
index c46d4c0942cfa6c71691138a509b07c03f9f2ede..3273140543a727de9a7a1157ddee6c669715e0ad 100644
--- a/libraries/io/tr_10GbE/src/vhdl/tr_10GbE.vhd
+++ b/libraries/io/tr_10GbE/src/vhdl/tr_10GbE.vhd
@@ -65,7 +65,7 @@ ENTITY tr_10GbE IS
     g_sim                    : BOOLEAN;
     g_sim_level              : NATURAL := 1; -- 0 = use IP; 1 = use fast serdes model
     g_nof_macs               : NATURAL;
-    g_use_mdio               : BOOLEAN;
+    g_use_mdio               : BOOLEAN := FALSE;
     g_mdio_epcs_dis          : BOOLEAN := FALSE; -- TRUE disables EPCS on init; e.g. to target a 10GbE card in PC that does not support it 
     g_tx_fifo_fill           : NATURAL := 10;    -- Release tx packet only when sufficiently data is available, 
     g_tx_fifo_size           : NATURAL := 256;   -- 2 * 32b * 256 = 2 M9K (DP interface has 64b data, so at least 2 M9K needed)