diff --git a/_docs/060_faq.md b/_docs/060_faq.md
index 9959a4f..0a34868 100644
--- a/_docs/060_faq.md
+++ b/_docs/060_faq.md
@@ -130,6 +130,18 @@ If you changed files which are matched by `.yadm/encrypt`, you must re-run `yadm
 encrypt` to generate a new version of `.yadm/files.gpg`. Then `.yadm/files.gpg`
 can be added to a new commit.
 
+### Why do I get the error `Inappropriate ioctl for device` when encrypting.
+
+If you get the error
+`command get_passphrase failed: Inappropriate ioctl for device`
+when running `yadm encrypt`, **gpg** is having trouble identifying the tty to
+use. The environment variable `GPG_TTY` can be used to help **gpg** out. Export
+this variable to your shell in your login scripts.
+
+```
+export GPG_TTY=$(tty)
+```
+
 ### Can I use **yadm** and **git-crypt**?
 
 There is an experimental version of **yadm** which can use **git-crypt**. You