diff --git a/libavcodec/wavpack.c b/libavcodec/wavpack.c
index 53ba34b69d..5a54f7d0e2 100644
--- a/libavcodec/wavpack.c
+++ b/libavcodec/wavpack.c
@@ -388,6 +388,7 @@ static int wavpack_decode_frame(AVCodecContext *avctx,
     memset(s->decorr, 0, MAX_TERMS * sizeof(Decorr));
 
     s->samples = LE_32(buf); buf += 4;
+    if(!s->samples) return buf_size;
     /* should not happen but who knows */
     if(s->samples * 2 * avctx->channels > AVCODEC_MAX_AUDIO_FRAME_SIZE){
         av_log(avctx, AV_LOG_ERROR, "Packet size is too big to be handled in lavc!\n");
diff --git a/libavformat/wv.c b/libavformat/wv.c
index e601c05fcb..86b7a7bd9c 100644
--- a/libavformat/wv.c
+++ b/libavformat/wv.c
@@ -118,15 +118,15 @@ static int wv_read_block_header(AVFormatContext *ctx, ByteIOContext *pb)
     if(!wc->chan) wc->chan = chan;
     if(!wc->rate) wc->rate = rate;
 
-    if(bpp != wc->bpp){
+    if(wc->flags && bpp != wc->bpp){
         av_log(ctx, AV_LOG_ERROR, "Bits per sample differ, this block: %i, header block: %i\n", bpp, wc->bpp);
         return -1;
     }
-    if(chan != wc->chan){
+    if(wc->flags && chan != wc->chan){
         av_log(ctx, AV_LOG_ERROR, "Channels differ, this block: %i, header block: %i\n", chan, wc->chan);
         return -1;
     }
-    if(rate != wc->rate){
+    if(wc->flags && rate != wc->rate){
         av_log(ctx, AV_LOG_ERROR, "Sampling rate differ, this block: %i, header block: %i\n", rate, wc->rate);
         return -1;
     }