diff --git a/include/mbedtls/legacy_or_psa.h b/include/mbedtls/legacy_or_psa.h
index fe87399e77..f872ddaf1f 100644
--- a/include/mbedtls/legacy_or_psa.h
+++ b/include/mbedtls/legacy_or_psa.h
@@ -1,7 +1,8 @@
 /**
  *  Macros to express dependencies for code and tests that may use either the
- *  legacy API or PSA in various builds; mostly for internal use.
- *
+ *  legacy API or PSA in various builds. This whole header file is currently
+ *  for internal use only and both the header file and the macros it defines
+ *  may change or be removed without notice.
  */
 /*
  *  Copyright The Mbed TLS Contributors