diff --git a/README.md b/README.md
index 57b5710..a399e22 100644
--- a/README.md
+++ b/README.md
@@ -22,20 +22,21 @@ saving a file and to run `do-reformat.sh` when you hit `<F1>`.
 
 ## Supported programming languages and file formats
 
-- python
+<!-- please keep this list sorted alphabetically -->
+
+- css
+- dart
 - go
-- javascript
-- typescript
-- vue
-- css
-- php
 - html
+- javascript
 - jsx
-- tsx
-- css
+- php
+- python
 - scss
 - sh
-- dart
+- tsx
+- typescript
+- vue
 
 Python uses `black`; go uses `gofmt`; dart uses `dart format`.  The rest use
 `prettier`.  Adding new programming languages is easy, assuming they have a