diff --git a/src/liblzma/api/lzma/vli.h b/src/liblzma/api/lzma/vli.h
index 6b604392..097801a4 100644
--- a/src/liblzma/api/lzma/vli.h
+++ b/src/liblzma/api/lzma/vli.h
@@ -71,7 +71,8 @@ typedef uint64_t lzma_vli;
  * for example in the uncompressed_size and compressed_size variables.
  *
  * \return      True if the integer is representable as VLI or if it
- *              indicates unknown value.
+ *              indicates unknown value. False if the integer cannot be
+ *              represented as VLI.
  */
 #define lzma_vli_is_valid(vli) \
 	((vli) <= LZMA_VLI_MAX || (vli) == LZMA_VLI_UNKNOWN)
@@ -87,12 +88,12 @@ typedef uint64_t lzma_vli;
  * integer has been encoded.
  *
  * \param       vli       Integer to be encoded
- * \param       vli_pos   How many VLI-encoded bytes have already been written
+ * \param[out]  vli_pos   How many VLI-encoded bytes have already been written
  *                        out. When starting to encode a new integer in
  *                        multi-call mode, *vli_pos must be set to zero.
  *                        To use single-call encoding, set vli_pos to NULL.
- * \param       out       Beginning of the output buffer
- * \param       out_pos   The next byte will be written to out[*out_pos].
+ * \param[out]  out       Beginning of the output buffer
+ * \param[out]  out_pos   The next byte will be written to out[*out_pos].
  * \param       out_size  Size of the out buffer; the first byte into
  *                        which no data is written to is out[out_size].
  *
@@ -122,15 +123,15 @@ extern LZMA_API(lzma_ret) lzma_vli_encode(lzma_vli vli, size_t *vli_pos,
  *
  * Like lzma_vli_encode(), this function has single-call and multi-call modes.
  *
- * \param       vli       Pointer to decoded integer. The decoder will
+ * \param[out]  vli       Pointer to decoded integer. The decoder will
  *                        initialize it to zero when *vli_pos == 0, so
  *                        application isn't required to initialize *vli.
- * \param       vli_pos   How many bytes have already been decoded. When
+ * \param[out]  vli_pos   How many bytes have already been decoded. When
  *                        starting to decode a new integer in multi-call
  *                        mode, *vli_pos must be initialized to zero. To
  *                        use single-call decoding, set vli_pos to NULL.
  * \param       in        Beginning of the input buffer
- * \param       in_pos    The next byte will be read from in[*in_pos].
+ * \param[out]  in_pos    The next byte will be read from in[*in_pos].
  * \param       in_size   Size of the input buffer; the first byte that
  *                        won't be read is in[in_size].
  *