diff --git a/docs/architecture/testing/invasive-testing.md b/docs/architecture/testing/invasive-testing.md
index de611a5..464f761 100644
--- a/docs/architecture/testing/invasive-testing.md
+++ b/docs/architecture/testing/invasive-testing.md
@@ -31,7 +31,7 @@
 
 ### Reliance on internal details
 
-In unit tests and in test programs, it's ok to include header files from `library/`. Do not define non-public interfaces in public headers (`include/mbedtls` has `*_internal.h` headers for legacy reasons, but this approach is deprecated). In contrast, sample programs must not include header files from `library/`.
+In unit tests and in test programs, it's ok to include internal header files from `library/`. Do not define non-public interfaces in public headers. In contrast, sample programs must not include header files from `library/`.
 
 Sometimes it makes sense to have unit tests on functions that aren't part of the public API. Declare such functions in `library/*.h` and include the corresponding header in the test code. If the function should be `static` for optimization but can't be `static` for testing, declare it as `MBEDTLS_STATIC_TESTABLE`, and make the tests that use it depend on `MBEDTLS_TEST_HOOKS` (see [“rules for compile-time options”](#rules-for-compile-time-options)).