diff --git a/README.md b/README.md
index d3977eb..79e492f 100644
--- a/README.md
+++ b/README.md
@@ -11,3 +11,7 @@ the work-in-progress cad model can be [here](https://cad.onshape.com/documents/4
 ---
 
 please contact [me](https://github.com/aslakstubsgaard) if you want to contribute.
+
+---
+
+this work and the cad model is under the GNU General Public License v3.0