diff --git a/demux/demux_lavf.c b/demux/demux_lavf.c
index da095dec6b1dd..f303fd9782794 100644
--- a/demux/demux_lavf.c
+++ b/demux/demux_lavf.c
@@ -438,7 +438,7 @@ static int lavf_check_file(demuxer_t *demuxer, enum demux_check check)
 
     const AVInputFormat *forced_format = NULL;
     const char *format = lavfdopts->format;
-    if (!format)
+    if (!format || !format[0])
         format = s->lavf_type;
     if (!format)
         format = avdevice_format;