diff --git a/README.md b/README.md
index b02896a..2b1ec93 100644
--- a/README.md
+++ b/README.md
@@ -133,12 +133,14 @@ Complete diagram is Work-in-Progress.
 
 ### IMU placement
 
-Required IMU orientation on the drone is **FLU** (Forward, Left, Up):
+Required IMU orientation on the drone is **FLU** (Forward, Left, Up)⁵:
 
-<img src="docs/img/flu.svg" width=400 alt="IMU orientation">
+<img src="docs/img/flu.svg" width=400 alt="GY-91 axis">
 
 In case of using **FRD** orientation (Forward, Right, Down), use [the code for rotation](https://gist.github.com/okalachev/713db47e31bce643dbbc9539d166ce98).
 
+*⁵ — This X/Y/Z IMU axis orientation is used in the Flix IMU library, internal accel/gyro/mag axes differ.*
+
 ## Version 0
 
 See the information on the obsolete version 0 in the [corresponding article](docs/version0.md).