diff --git a/README.md b/README.md
index a975fae..ccac278 100644
--- a/README.md
+++ b/README.md
@@ -303,6 +303,9 @@ Settings → Pair iOS app: scan the QR code, or tap "Copy pairing code" and past
 it into the app's "Enter manually". Self-signed certificates are pinned during
 pairing.
 
+The iOS app is currently in beta testing. For an invite, email
+[engineroom@redetzke.aero](mailto:engineroom@redetzke.aero).
+
 ## Development
 
 On macOS (or any non-Linux system), `make dev` starts the app on