diff --git a/README.md b/README.md
index e552391..70cc550 100644
--- a/README.md
+++ b/README.md
@@ -24,4 +24,19 @@ Add to a flake:
 }
 ```
 
-The package output is `packages.x86_64-linux.oryxis` (also the default).
+The package output is `packages.<system>.oryxis` (also the default), for
+`x86_64-linux` and `aarch64-linux`.
+
+## Updating
+
+To bump to a new upstream release, edit `package.nix`:
+
+1. Set `version` to the new tag (without the `v` prefix).
+2. Refresh both `hash` values:
+
+   ```sh
+   nix-prefetch-url --type sha256 https://github.com/wilsonglasser/oryxis/releases/download/v<version>/oryxis-linux-x86_64.tar.gz | xargs nix hash convert --hash-algo sha256
+   nix-prefetch-url --type sha256 https://github.com/wilsonglasser/oryxis/releases/download/v<version>/oryxis-linux-aarch64.tar.gz | xargs nix hash convert --hash-algo sha256
+   ```
+
+3. `nix build` to verify.