diff --git a/src/decoder/plugins/Mpg123DecoderPlugin.cxx b/src/decoder/plugins/Mpg123DecoderPlugin.cxx
index 3ae5e86f8..c0ad31a81 100644
--- a/src/decoder/plugins/Mpg123DecoderPlugin.cxx
+++ b/src/decoder/plugins/Mpg123DecoderPlugin.cxx
@@ -353,6 +353,10 @@ mpd_mpg123_stream_decode(DecoderClient &client, InputStream &is)
 	};
 
 	mpd_mpg123_open_stream(*handle, iohandle);
+
+	if (is.KnownSize())
+	    mpg123_set_filesize(handle, is.GetSize());
+
 	Decode(client, *handle, is.IsSeekable());
 }