diff --git a/include/mbedtls/sha512.h b/include/mbedtls/sha512.h
index e8d0ab7c1..b6bee9a82 100644
--- a/include/mbedtls/sha512.h
+++ b/include/mbedtls/sha512.h
@@ -103,7 +103,11 @@ void mbedtls_sha512_clone( mbedtls_sha512_context *dst,
  *
  * \param ctx      The SHA-512 context to use. This must be initialized.
  * \param is384    Determines which function to use. This must be
- *                 either \c for SHA-512, or \c 1 for SHA-384.
+ *                 either \c 0 for SHA-512, or \c 1 for SHA-384.
+ *
+ * \note           When MBEDTLS_SHA512_NO_SHA384 is defined, \p is384 must be
+ *                 0, or the function will return
+ *                 MBEDTLS_ERR_SHA512_BAD_INPUT_DATA.
  *
  * \return         \c 0 on success.
  * \return         A negative error code on failure.
@@ -171,6 +175,9 @@ int mbedtls_internal_sha512_process( mbedtls_sha512_context *ctx,
  * \param ctx      The SHA-512 context to use. This must be initialized.
  * \param is384    Determines which function to use. This must be either
  *                 \c 0 for SHA-512 or \c 1 for SHA-384.
+ *
+ * \note           When MBEDTLS_SHA512_NO_SHA384 is defined, \p is384 must be
+ *                 0, or the function will fail to work.
  */
 MBEDTLS_DEPRECATED void mbedtls_sha512_starts( mbedtls_sha512_context *ctx,
                                                int is384 );
@@ -241,6 +248,10 @@ MBEDTLS_DEPRECATED void mbedtls_sha512_process(
  * \param is384    Determines which function to use. This must be either
  *                 \c 0 for SHA-512, or \c 1 for SHA-384.
  *
+ * \note           When MBEDTLS_SHA512_NO_SHA384 is defined, \p is384 must be
+ *                 0, or the function will return
+ *                 MBEDTLS_ERR_SHA512_BAD_INPUT_DATA.
+ *
  * \return         \c 0 on success.
  * \return         A negative error code on failure.
  */
@@ -275,6 +286,9 @@ int mbedtls_sha512_ret( const unsigned char *input,
  *                 be a writable buffer of length \c 64 Bytes.
  * \param is384    Determines which function to use. This must be either
  *                 \c 0 for SHA-512, or \c 1 for SHA-384.
+ *
+ * \note           When MBEDTLS_SHA512_NO_SHA384 is defined, \p is384 must be
+ *                 0, or the function will fail to work.
  */
 MBEDTLS_DEPRECATED void mbedtls_sha512( const unsigned char *input,
                                         size_t ilen,