diff --git a/readme.md b/readme.md
index e2d8862..d8a3eb0 100644
--- a/readme.md
+++ b/readme.md
@@ -22,7 +22,7 @@ This needs to be done at every boot.
 
 Kudos to danjperron, cmp. https://www.raspberrypi.org/forums/viewtopic.php?f=98&t=224533&hilit=rs+485#p1383709
 
-(Note, please: I do not derive from this software, I use it in an unchanged way. It is not integrated into my sources, it just needs to be called once the RPi has booted.)
+(Note, please: This software is under the GPL 3.0 license. However, I do not derive from this software, I use it in an unchanged way. It is not integrated into my sources, it just needs to be called once the RPi has booted.)
 
 ## Pinout