diff --git a/README.md b/README.md
index 284f076..4e591f8 100644
--- a/README.md
+++ b/README.md
@@ -30,7 +30,8 @@
 * Install the relevant Nerd Font and set it as default in your terminal app.
 * Clone this repo.
 * `cargo build --release`
-* `mv target/release/zsh-rust-git-prompt <bindir>` where `<bindir>` is in `PATH`.
+* `rm <bindir>/zsh-rust-git-prompt` — **MANDATORY** on Apple Silicon, optional on Intel. Simply copying or moving the new binary over the top of the old one will cause a code signature mismatch and lead to obscure `zsh: killed` errors — see [Updating Mac Software](https://developer.apple.com/documentation/security/updating_mac_software). Removing the old binary first flushes its code signature cache.
+* `cp target/release/zsh-rust-git-prompt <bindir>` where `<bindir>` is in `PATH`.
 * Add this to your `.zshrc`:
 
   ```zsh