diff --git a/packages/babel-helper-bindify-decorators/src/index.js b/packages/babel-helper-bindify-decorators/src/index.ts
similarity index 93%
rename from packages/babel-helper-bindify-decorators/src/index.js
rename to packages/babel-helper-bindify-decorators/src/index.ts
index 74029e6375..3a88b98db2 100644
--- a/packages/babel-helper-bindify-decorators/src/index.js
+++ b/packages/babel-helper-bindify-decorators/src/index.ts
@@ -2,8 +2,8 @@ import type { NodePath } from "@babel/traverse";
 import * as t from "@babel/types";
 
 export default function bindifyDecorators(
-  decorators: Array<NodePath>,
-): Array<NodePath> {
+  decorators: ReadonlyArray<NodePath<t.Decorator>>,
+): void {
   for (const decoratorPath of decorators) {
     const decorator = decoratorPath.node;
     const expression = decorator.expression;