diff --git a/libraries/WiFi/arch/avr/utility/spi_drv.cpp b/libraries/WiFi/arch/avr/utility/spi_drv.cpp
index b5a1d0696..306524df9 100644
--- a/libraries/WiFi/arch/avr/utility/spi_drv.cpp
+++ b/libraries/WiFi/arch/avr/utility/spi_drv.cpp
@@ -15,7 +15,7 @@ extern "C" {
 #define SLAVEREADY  7  // handshake pin
 #define WIFILED     9  // led on wifi shield
 
-#define DELAY_SPI(X) { int ii=0; do { asm volatile("nop"); } while (++ii < X); }
+#define DELAY_SPI(X) { int ii=0; do { asm volatile("nop"); } while (++ii < (X*F_CPU/16000000)); }
 #define DELAY_TRANSFER() DELAY_SPI(10)
 
 void SpiDrv::begin()
diff --git a/libraries/WiFi/arch/sam/utility/spi_drv.cpp b/libraries/WiFi/arch/sam/utility/spi_drv.cpp
index c037a32e4..306524df9 100644
--- a/libraries/WiFi/arch/sam/utility/spi_drv.cpp
+++ b/libraries/WiFi/arch/sam/utility/spi_drv.cpp
@@ -15,7 +15,7 @@ extern "C" {
 #define SLAVEREADY  7  // handshake pin
 #define WIFILED     9  // led on wifi shield
 
-#define DELAY_SPI(X) { int ii=0; do { asm volatile("nop"); } while (++ii < X*6); }
+#define DELAY_SPI(X) { int ii=0; do { asm volatile("nop"); } while (++ii < (X*F_CPU/16000000)); }
 #define DELAY_TRANSFER() DELAY_SPI(10)
 
 void SpiDrv::begin()