diff --git a/src/utility/w5100.h b/src/utility/w5100.h
index 099556a6..6b2620e5 100644
--- a/src/utility/w5100.h
+++ b/src/utility/w5100.h
@@ -17,8 +17,13 @@
 #include <Arduino.h>
 #include <SPI.h>
 
+// add SPI_ETHERNET_SPEED to allow for an explicit change of SPI speed
+#ifndef SPI_ETHERNET_SPEED
+#define SPI_ETHERNET_SPEED 14000000
+#endif
+
 // Safe for all chips
-#define SPI_ETHERNET_SETTINGS SPISettings(14000000, MSBFIRST, SPI_MODE0)
+#define SPI_ETHERNET_SETTINGS SPISettings(SPI_ETHERNET_SPEED, MSBFIRST, SPI_MODE0)
 
 // Safe for W5200 and W5500, but too fast for W5100
 // Uncomment this if you know you'll never need W5100 support.