diff --git a/libavformat/wavdec.c b/libavformat/wavdec.c
index 00856a5eca..78e37b88d7 100644
--- a/libavformat/wavdec.c
+++ b/libavformat/wavdec.c
@@ -874,8 +874,7 @@ static int w64_read_header(AVFormatContext *s)
     uint8_t guid[16];
     int ret;
 
-    avio_read(pb, guid, 16);
-    if (memcmp(guid, ff_w64_guid_riff, 16))
+    if (avio_read(pb, guid, 16) != 16 || memcmp(guid, ff_w64_guid_riff, 16))
         return AVERROR_INVALIDDATA;
 
     /* riff + wave + fmt + sizes */