diff --git a/docs/galileorevd.md b/docs/galileorevd.md
index 16d59d8..42201a5 100644
--- a/docs/galileorevd.md
+++ b/docs/galileorevd.md
@@ -6,6 +6,7 @@ Application Processor, a 32-bit Intel Pentium-class system on a chip.
 
 The rev D board has the following limitations in libmraa:
 
+- gpio 13 will not switch the LED as it's a different Gpio, use raw gpio '3' to do this
 - gpio register access via /dev/uio is limited to pin2 and 3
 - gpio interupts will only work on GPIO_EDGE_BOTH
 - adc kernel module will return 12bit number. MRAA defaults shift this to 10bits