diff --git a/libavcodec/pngenc.c b/libavcodec/pngenc.c
index f6ad830cd9..0bae2acfb9 100644
--- a/libavcodec/pngenc.c
+++ b/libavcodec/pngenc.c
@@ -817,7 +817,7 @@ static int encode_apng(AVCodecContext *avctx, AVPacket *pkt,
     int ret;
     int enc_row_size;
     size_t max_packet_size;
-    APNGFctlChunk fctl_chunk;
+    APNGFctlChunk fctl_chunk = {0};
 
     if (pict && avctx->codec_id == AV_CODEC_ID_APNG && s->color_type == PNG_COLOR_TYPE_PALETTE) {
         uint32_t checksum = ~av_crc(av_crc_get_table(AV_CRC_32_IEEE_LE), ~0U, pict->data[1], 256 * sizeof(uint32_t));