diff --git a/ChangeLog b/ChangeLog
index 5d7236472..68427ca1f 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -61,6 +61,11 @@ Changes
 INTERNAL NOTE: need to bump soversion of libmbedtls:
 - added new member 'mtu' to public 'mbedtls_ssl_conf' structure
 
+Changes
+   * Add warnings to the documentation of the HKDF module to reduce the risk
+     of misusing the mbedtls_hkdf_extract() and mbedtls_hkdf_expand()
+     functions. Fixes #1775. Reported by Brian J. Murray.
+
 = mbed TLS 2.12.0 branch released 2018-07-25
 
 Security
diff --git a/include/mbedtls/hkdf.h b/include/mbedtls/hkdf.h
index 6833e7272..e6ed7cde9 100644
--- a/include/mbedtls/hkdf.h
+++ b/include/mbedtls/hkdf.h
@@ -73,6 +73,11 @@ int mbedtls_hkdf( const mbedtls_md_info_t *md, const unsigned char *salt,
  *  \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);
@@ -97,10 +102,15 @@ int mbedtls_hkdf_extract( const mbedtls_md_info_t *md,
  *  \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 usually,
- *                    the output from the HKDF extract step.
+ *  \param  prk       A pseudorandom key of at least md.size bytes. \p prk is
+ *                    usually the output from the HKDF extract step.
  *  \param  prk_len   The length in bytes of \p prk.
  *  \param  info      An optional context and application specific information
  *                    string. This can be a zero-length string.