diff --git a/include/mbedtls/hkdf.h b/include/mbedtls/hkdf.h
index 235c5ad..e6ed7cd 100644
--- a/include/mbedtls/hkdf.h
+++ b/include/mbedtls/hkdf.h
@@ -73,6 +73,11 @@
  *  \brief  Take the input keying material \p ikm and extract from it a
  *          fixed-length pseudorandom key \p prk.
  *
+ *  \warning    This function should only be used if the security of it has been
+ *              studied and established in that particular context (eg. TLS 1.3
+ *              key schedule). For standard HKDF security guarantees use
+ *              \c mbedtls_hkdf instead.
+ *
  *  \param       md        A hash function; md.size denotes the length of the
  *                         hash function output in bytes.
  *  \param       salt      An optional salt value (a non-secret random value);
@@ -97,6 +102,11 @@
  *  \brief  Expand the supplied \p prk into several additional pseudorandom
  *          keys, which is the output of the HKDF.
  *
+ *  \warning    This function should only be used if the security of it has been
+ *              studied and established in that particular context (eg. TLS 1.3
+ *              key schedule). For standard HKDF security guarantees use
+ *              \c mbedtls_hkdf instead.
+ *
  *  \param  md        A hash function; md.size denotes the length of the hash
  *                    function output in bytes.
  *  \param  prk       A pseudorandom key of at least md.size bytes. \p prk is