diff --git a/api/cpp/include/slint-testing.h b/api/cpp/include/slint-testing.h
index b2db3da12..4711e7342 100644
--- a/api/cpp/include/slint-testing.h
+++ b/api/cpp/include/slint-testing.h
@@ -10,6 +10,11 @@
 #ifdef SLINT_FEATURE_TESTING
 #    ifdef SLINT_FEATURE_EXPERIMENTAL
 
+/// Use the functions and classes in this namespace for in-process UI testing.
+///
+/// This module is still experimental - it's API is subject to changes and not stabilized yet. To
+/// use the module, you must enable the `SLINT_FEATURE_EXPERIMENTAL=ON` and `SLINT_FEATURE_TESTING`
+/// CMake options.
 namespace slint::testing {
 
 using slint::cbindgen_private::AccessibleRole;