diff --git a/libavformat/file.c b/libavformat/file.c
index d2cb5302d4..9b60a5f1f8 100644
--- a/libavformat/file.c
+++ b/libavformat/file.c
@@ -73,6 +73,8 @@ static int file_write(URLContext *h, unsigned char *buf, int size)
 static int64_t file_seek(URLContext *h, int64_t pos, int whence)
 {
     int fd = (intptr_t) h->priv_data;
+    if (whence != SEEK_SET && whence != SEEK_CUR && whence != SEEK_END)
+        return AVERROR_NOTSUPP;
     return lseek(fd, pos, whence);
 }