diff --git a/README.md b/README.md
index e438cf8..e6dba12 100644
--- a/README.md
+++ b/README.md
@@ -344,6 +344,8 @@ The same approach as above is also used for alert providers.
 
 As well as being my work, I have also gratefully received feature patches from Steven, M1SDH.
 
+The project contains GeoJSON files for CQ and ITU zones, in the `/datafiles/` directory. These are MIT-licenced and, to my knowledge, created by HA8TKS for his CQ and ITU zone layers for Leaflet.
+
 The project contains a self-hosted copy of Font Awesome's free library, in the `/webassets/fa/` directory. This is subject to Font Awesome's licence and is not covered by the overall licence declared in the `LICENSE` file. This approach was taken in preference to using their hosted kits due to the popularity of this project exceeding the page view limit for their free hosted offering.
 
 The project contains a set of flag icons generated using the "Noto Color Emoji" font on a Debian system, in the `/webassets/img/flags/` directory.