diff --git a/libavcodec/hnm4video.c b/libavcodec/hnm4video.c
index a64dbb1746..9e1ac49ddc 100644
--- a/libavcodec/hnm4video.c
+++ b/libavcodec/hnm4video.c
@@ -375,6 +375,7 @@ static void hnm_update_palette(AVCodecContext *avctx, uint8_t *src,
             hnm->palette[writeoffset] = bytestream2_get_be24(&gb);
             if (!eight_bit_colors)
                 hnm->palette[writeoffset] <<= 2;
+            hnm->palette[writeoffset] |= (0xFFU << 24);
             count--;
             writeoffset++;
         }