diff --git a/lib/babel-packages.js.flow b/lib/babel-packages.js.flow
index e500b5fd93e5..cae0200500f9 100644
--- a/lib/babel-packages.js.flow
+++ b/lib/babel-packages.js.flow
@@ -49,3 +49,13 @@ declare module "@babel/helper-get-function-arity" {
     node: BabelNodeFunction
   ): number;
 }
+
+declare module "@babel/helper-annotate-as-pure" {
+  declare export default function annotateAsPure(
+    pathOrNode:
+      | BabelNode
+      | {
+          node: BabelNode,
+        }
+  ): void;
+}
diff --git a/packages/babel-helper-annotate-as-pure/src/index.js b/packages/babel-helper-annotate-as-pure/src/index.ts
similarity index 52%
rename from packages/babel-helper-annotate-as-pure/src/index.js
rename to packages/babel-helper-annotate-as-pure/src/index.ts
index 1f443b0b8edd..bee16cd7a162 100644
--- a/packages/babel-helper-annotate-as-pure/src/index.js
+++ b/packages/babel-helper-annotate-as-pure/src/index.ts
@@ -1,13 +1,16 @@
 import * as t from "@babel/types";
+import type { Node } from "@babel/types";
 
 const PURE_ANNOTATION = "#__PURE__";
 
-const isPureAnnotated = ({ leadingComments }) =>
+const isPureAnnotated = ({ leadingComments }: Node): boolean =>
   !!leadingComments &&
   leadingComments.some(comment => /[@#]__PURE__/.test(comment.value));
 
-export default function annotateAsPure(pathOrNode) {
-  const node = pathOrNode.node || pathOrNode;
+export default function annotateAsPure(
+  pathOrNode: Node | { node: Node },
+): void {
+  const node = pathOrNode["node"] || pathOrNode;
   if (isPureAnnotated(node)) {
     return;
   }