diff --git a/libavcodec/libspeexdec.c b/libavcodec/libspeexdec.c
index 7bff4255be392d39e669b21cacb2ac65d40cdaac..686c9e8142e1026c068c2b5c716b56c46bc6b064 100644
--- a/libavcodec/libspeexdec.c
+++ b/libavcodec/libspeexdec.c
@@ -54,6 +54,7 @@ static av_cold int libspeex_decode_init(AVCodecContext *avctx)
     if (s->header) {
         avctx->sample_rate = s->header->rate;
         avctx->channels    = s->header->nb_channels;
+        s->frame_size      = s->header->frame_size;
 
         mode = speex_lib_get_mode(s->header->mode);
         if (!mode) {