diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 0c5d6f4..46b73c7 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -9,6 +9,7 @@
 - `entr` to watch for file changes
 - `xdg-open` link handler to invoke browser
 - `libgd` (`php-gd`, `phpX.Y-gd`) for downsizing images
+- `zstd` to archive files (when using `--archive` flag)
 - (Optional) `doxygen` to generate documentation
 
 ### Official repositories