diff --git a/include/mbedtls/config.h b/include/mbedtls/config.h
index 751fa0a..a00eec5 100644
--- a/include/mbedtls/config.h
+++ b/include/mbedtls/config.h
@@ -566,6 +566,23 @@
 //#define MBEDTLS_TEST_CONSTANT_FLOW_MEMSAN
 
 /**
+ * \def MBEDTLS_TEST_CONSTANT_FLOW_VALGRIND
+ *
+ * Enable testing of the constant-flow nature of some sensitive functions with
+ * valgrind's memcheck tool. This causes some existing tests to also test
+ * non-functional properties of the code under test.
+ *
+ * This setting requires valgrind headers for building, and is only useful for
+ * testing if the tests suites are run with valgrind's memcheck.
+ *
+ * \warning This macro is only used for extended testing; it is not considered
+ * part of the library's API, so it may change or disappear at any time.
+ *
+ * Uncomment to enable testing of the constant-flow nature of selected code.
+ */
+//#define MBEDTLS_TEST_CONSTANT_FLOW_VALGRIND
+
+/**
  * \def MBEDTLS_TEST_NULL_ENTROPY
  *
  * Enables testing and use of mbed TLS without any configured entropy sources.