diff --git a/shell-completion/README.md b/shell-completion/README.md
index fc6d64db6..610c3cda0 100644
--- a/shell-completion/README.md
+++ b/shell-completion/README.md
@@ -54,3 +54,28 @@ The Bash completion script is generated (GNU make) by parsing output of `hledger
 `hledger -h`, and `hledger <cmd> -h`. The script also uses `hledger accounts` for
 account name completion. I propose that the Makefile is not run at every built
 but rather manually when the CLI changes.
+
+Completion scripts for other shells (e.g. Fish or Zsh)
+------------------------------------------------------
+
+You're welcome to add completion scripts for other shells. It should not be too
+hard! All available hledger options and commands are already there (generated by
+the Makefile).
+
+The generated text files with options and commands are: `commands.txt`,
+`generic-options.txt`, and `options-*.txt` where `*` is the subcommand.
+
+Instructions to add support for another shell:
+
+1. Create e.g. `hledger-completion.fish.m4` as a template file.
+
+2. Add a Make rule to transform it to `hledger-completion.fish`.
+
+3. Use m4 commands to include hledger options and commands into your script
+   template. See `hledger-completion.bash.m4` as a reference.
+
+4. Use `make` and then `make hledger-completion.fish` to create and test the
+   completion script.
+
+5. Finally, if everything is working, also add the generated artifact
+   `hledger-completion.fish` to the repo so that people can use it directly.