diff --git a/cyw43-firmware/README.md b/cyw43-firmware/README.md
index ccd38be2..10a6b5d0 100644
--- a/cyw43-firmware/README.md
+++ b/cyw43-firmware/README.md
@@ -1,4 +1,4 @@
-# WiFi firmware
+# WiFi + Bluetooth firmware blobs
 
 Firmware obtained from https://github.com/georgerobotics/cyw43-driver/tree/main/firmware
 
@@ -8,3 +8,7 @@ Licensed under the [Infineon Permissive Binary License](./LICENSE-permissive-bin
 
 * 2023-08-21: synced with `a1dc885` - Update 43439 fw + clm to come from `wb43439A0_7_95_49_00_combined.h` + add Bluetooth firmware
 * 2023-07-28: synced with `ad3bad0` - Update 43439 fw from 7.95.55 to 7.95.62
+
+## Notes
+
+If you update these files, please update the lengths in the `tests/rp/src/bin/cyw43_perf.rs` test (which relies on these files running from RAM).