diff --git a/libavformat/wav.c b/libavformat/wav.c
index e8c5b44e39..7588baf265 100644
--- a/libavformat/wav.c
+++ b/libavformat/wav.c
@@ -105,8 +105,11 @@ int put_wav_header(ByteIOContext *pb, AVCodecContext *enc)
         put_le16(pb, 2); /* wav_extra_size */
         hdrsize += 2;
         put_le16(pb, ((enc->block_align - 4 * enc->channels) / (4 * enc->channels)) * 8 + 1); /* wSamplesPerBlock */
-    } else
-        put_le16(pb, 0); /* wav_extra_size */
+    } else {
+        put_le16(pb, enc->extradata_size);
+        put_buffer(pb, enc->extradata, enc->extradata_size);
+        hdrsize += enc->extradata_size;
+    }
 
     return hdrsize;
 }