diff --git a/libavcodec/movtextenc.c b/libavcodec/movtextenc.c
index 9b0a6c5bce..5d91e94f75 100644
--- a/libavcodec/movtextenc.c
+++ b/libavcodec/movtextenc.c
@@ -75,7 +75,7 @@ static av_cold int mov_text_encode_init(AVCodecContext *avctx)
     MovTextContext *s = avctx->priv_data;
 
     avctx->extradata_size = sizeof text_sample_entry;
-    avctx->extradata = av_mallocz(avctx->extradata_size);
+    avctx->extradata = av_mallocz(avctx->extradata_size + FF_INPUT_BUFFER_PADDING_SIZE);
     if (!avctx->extradata)
         return AVERROR(ENOMEM);