diff --git a/libavformat/utils.c b/libavformat/utils.c
index 20316af64b..445434c277 100644
--- a/libavformat/utils.c
+++ b/libavformat/utils.c
@@ -559,7 +559,7 @@ int av_open_input_file(AVFormatContext **ic_ptr, const char *filename,
         if (buf_size > 0) {
             url_setbufsize(pb, buf_size);
         }
-        if ((err = ff_probe_input_buffer(&pb, &fmt, filename, logctx, 0, logctx ? (*ic_ptr)->probesize : 0)) < 0) {
+        if (!fmt && (err = ff_probe_input_buffer(&pb, &fmt, filename, logctx, 0, logctx ? (*ic_ptr)->probesize : 0)) < 0) {
             goto fail;
         }
     }