diff --git a/cocotbext/eth/mii.py b/cocotbext/eth/mii.py
index f40f3cd..055c50d 100644
--- a/cocotbext/eth/mii.py
+++ b/cocotbext/eth/mii.py
@@ -293,6 +293,8 @@ class MiiPhy:
         self.tx_clk = tx_clk
         self.rx_clk = rx_clk
 
+        super().__init__(*args, **kwargs)
+
         self.tx = MiiSink(txd, tx_er, tx_en, tx_clk, reset)
         self.rx = MiiSource(rxd, rx_er, rx_dv, rx_clk, reset)
 
diff --git a/cocotbext/eth/rgmii.py b/cocotbext/eth/rgmii.py
index d6c8260..cd33b92 100644
--- a/cocotbext/eth/rgmii.py
+++ b/cocotbext/eth/rgmii.py
@@ -319,6 +319,8 @@ class RgmiiPhy:
         self.tx_clk = tx_clk
         self.rx_clk = rx_clk
 
+        super().__init__(*args, **kwargs)
+
         self.tx = RgmiiSink(txd, tx_ctl, tx_clk, reset)
         self.rx = RgmiiSource(rxd, rx_ctl, rx_clk, reset)