diff --git a/vp9/encoder/vp9_bitstream.c b/vp9/encoder/vp9_bitstream.c
index e4f816e550d65a30da9e97e10ac037648ed44d8f..2a1836f40cc8cc7ea905655b2b3798d29d949f9f 100644
--- a/vp9/encoder/vp9_bitstream.c
+++ b/vp9/encoder/vp9_bitstream.c
@@ -1276,7 +1276,8 @@ void vp9_pack_bitstream(VP9_COMP *cpi, uint8_t *dest, size_t *size) {
 
   first_part_size = write_compressed_header(cpi, data);
   data += first_part_size;
-  vp9_wb_write_literal(&saved_wb, first_part_size, 16);
+  // TODO(jbb): Figure out what to do if first_part_size > 16 bits.
+  vp9_wb_write_literal(&saved_wb, (int)first_part_size, 16);
 
   data += encode_tiles(cpi, data);