README.md | 6 +++++-

diff --git a/README.md b/README.md
index 3ca10820e6b8b6a778b4185cb3a4fb2b50388cf0..af614d8e8eeecc66605e25e05547da59a97c91a4 100644
--- a/README.md
+++ b/README.md
@@ -385,7 +385,11 @@ #### copy file paths when X is missing
 
 A very common scenario on headless remote servers connected via SSH. As the clipboard is missing, `nnn` copies the path names to the tmp file `/tmp/nnncp`.
 
-To use the copied paths from the cmdline, use command substitution:
+`nnn` needs to know X is unavailable:
+
+    export NNN_NO_X=1
+
+Use <kbd>^Y</kbd> and/or <kbd>^K</kbd> to copy file paths as usual. To use the copied paths from the cmdline, use command substitution:
 
     # bash/zsh
     ls -ltr `cat /tmp/nnncp`