diff --git a/libavcodec/a52dec.c b/libavcodec/a52dec.c
index 0a7c0c552f..1bf7f8e0e2 100644
--- a/libavcodec/a52dec.c
+++ b/libavcodec/a52dec.c
@@ -162,6 +162,8 @@ static int a52_decode_frame(AVCodecContext *avctx,
         2, 1, 2, 3, 3, 4, 4, 5
     };
 
+    *data_size= 0;
+
     buf_ptr = buf;
     while (buf_size > 0) {
         len = s->inbuf_ptr - s->inbuf;