diff --git a/libavformat/unix.c b/libavformat/unix.c
index 5704155cf0..fed215a691 100644
--- a/libavformat/unix.c
+++ b/libavformat/unix.c
@@ -89,6 +89,7 @@ static int unix_open(URLContext *h, const char *filename, int flags)
     }
 
     s->fd = fd;
+    h->is_streamed = 1;
 
     return 0;