diff --git a/README.md b/README.md
index 007eece..31e1989 100644
--- a/README.md
+++ b/README.md
@@ -57,6 +57,7 @@ $ node destreamer.js --username username@example.com --outputDirectory "videos"
                 "https://web.microsoftstream.com/video/VIDEO-3"
 ```
 You can use an absolute path for `--outputDirectory`, for example `/mnt/videos`.
+Your video URLs **must** include the URL schema (the leading `https://`).
 
 To choose preferred video format and quality you can use the `-f` (`--format`) option. It exposes a native [`youtube-dl` parameter][4].
 If you do not pass this parameter then `youtube-dl` will download the best available quality for each video.