diff --git a/tests/make-in-docker.sh b/tests/make-in-docker.sh
index 77dc8ab..0ee08dc 100755
--- a/tests/make-in-docker.sh
+++ b/tests/make-in-docker.sh
@@ -8,6 +8,10 @@
 #
 # See also:
 # - scripts/docker_env.sh for general Docker prerequisites and other information.
+#
+# WARNING: the Dockerfile used by this script is no longer maintained! See
+# https://github.com/Mbed-TLS/mbedtls-test/blob/master/README.md#quick-start
+# for the set of Docker images we use on the CI.
 
 # Copyright The Mbed TLS Contributors
 # SPDX-License-Identifier: Apache-2.0