diff --git a/drivers/net/macb.c b/drivers/net/macb.c
index 6657d22926b55f4000c03095bb9b87af53247056..9c98338f746000da0edb0aa562e682e3b7fa99c4 100644
--- a/drivers/net/macb.c
+++ b/drivers/net/macb.c
@@ -417,10 +417,18 @@ static int macb_init(struct eth_device *netdev, bd_t *bd)
 
 	/* choose RMII or MII mode. This depends on the board */
 #ifdef CONFIG_RMII
+#ifdef CONFIG_AT91CAP9ADK
+	macb_writel(macb, USRIO, MACB_BIT(RMII) | MACB_BIT(CLKEN));
+#else
 	macb_writel(macb, USRIO, 0);
+#endif
+#else
+#ifdef CONFIG_AT91CAP9ADK
+	macb_writel(macb, USRIO, MACB_BIT(CLKEN));
 #else
 	macb_writel(macb, USRIO, MACB_BIT(MII));
 #endif
+#endif /* CONFIG_RMII */
 
 	if (!macb_phy_init(macb))
 		return -1;
diff --git a/drivers/net/macb.h b/drivers/net/macb.h
index c778e4ee493c94649180985546e1dbf889441e1e..f92a20c7015d04d496801ce7d9a5195095bbaac2 100644
--- a/drivers/net/macb.h
+++ b/drivers/net/macb.h
@@ -222,6 +222,12 @@
 #define MACB_TX_PAUSE_ZERO_OFFSET		3
 #define MACB_TX_PAUSE_ZERO_SIZE			1
 
+/* Bitfields in USRIO (AT91) */
+#define MACB_RMII_OFFSET			0
+#define MACB_RMII_SIZE				1
+#define MACB_CLKEN_OFFSET			1
+#define MACB_CLKEN_SIZE				1
+
 /* Bitfields in WOL */
 #define MACB_IP_OFFSET				0
 #define MACB_IP_SIZE				16