diff --git a/arch/arm/src/lpc17xx_40xx/lpc17_40_ethernet.c b/arch/arm/src/lpc17xx_40xx/lpc17_40_ethernet.c
index 939f4d76d2d..003eba909a0 100644
--- a/arch/arm/src/lpc17xx_40xx/lpc17_40_ethernet.c
+++ b/arch/arm/src/lpc17xx_40xx/lpc17_40_ethernet.c
@@ -2741,7 +2741,7 @@ static inline int lpc17_40_phyinit(struct lpc17_40_driver_s *priv)
 
   while ((lpc17_40_phyread(phyaddr, MII_DP83848C_STS) & 0x0001) == 0)
     {
-      up_udelay(40000);
+      usleep(40000);
     }
 #endif