diff --git a/packages/babel-helper-hoist-variables/README.md b/packages/babel-helper-hoist-variables/README.md
index 1ac18e57c5..5550490f13 100644
--- a/packages/babel-helper-hoist-variables/README.md
+++ b/packages/babel-helper-hoist-variables/README.md
@@ -1,5 +1,10 @@
 # @babel/helper-hoist-variables
 
+## API
+```javascript
+declare export default hoistVariables(path: NodePath, emit: Function, kind: "var" | "let" = "var");
+```
+
 ## Usage
 
 TODO