--- a/gst/isomp4/qtdemux.h
+++ b/gst/isomp4/qtdemux.h
@@ -112,7 +112,7 @@ struct _GstQTDemux {
   guint64 seek_offset;
 
   gboolean upstream_seekable;
-  gboolean upstream_size;
+  gint64 upstream_size;
 };
 
 struct _GstQTDemuxClass {
