diff --git a/README.md b/README.md
index 204506c6..fe34cf29 100644
--- a/README.md
+++ b/README.md
@@ -32,6 +32,7 @@ https://github.com/candle-usb/candleLight_fw/pull/176.
 
 STM32G431-based devices (e.g. CANable-MKS 2.0) are not yet supported.
 
+Currently, the firmware sends back an echo frame to the host when the frame is written to the CAN peripheral, and not when the frame is actually sent successfully on the bus. This affects timestamps, one-shot mode, and other edge cases.
 
 ## Known issues