diff --git a/packages/gatsby/src/bootstrap/__mocks__/resolve-module-exports.js b/packages/gatsby/src/bootstrap/__mocks__/resolve-module-exports.ts
similarity index 78%
rename from packages/gatsby/src/bootstrap/__mocks__/resolve-module-exports.js
rename to packages/gatsby/src/bootstrap/__mocks__/resolve-module-exports.ts
index 5c2454d82f97a..2ec1d9decca18 100644
--- a/packages/gatsby/src/bootstrap/__mocks__/resolve-module-exports.js
+++ b/packages/gatsby/src/bootstrap/__mocks__/resolve-module-exports.ts
@@ -2,7 +2,7 @@
 
 let mockResults = {}
 
-module.exports = input => {
+export const resolveModuleExports = (input: unknown): string[] | undefined => {
   // return a mocked result
   if (typeof input === `string`) {
     return mockResults[input]
diff --git a/packages/gatsby/src/bootstrap/__tests__/resolve-module-exports.js b/packages/gatsby/src/bootstrap/__tests__/resolve-module-exports.js
index aac8a6f128860..7c6ca196a1386 100644
--- a/packages/gatsby/src/bootstrap/__tests__/resolve-module-exports.js
+++ b/packages/gatsby/src/bootstrap/__tests__/resolve-module-exports.js
@@ -13,7 +13,7 @@ jest.mock(`gatsby-cli/lib/reporter`, () => {
 
 const fs = require(`fs`)
 const reporter = require(`gatsby-cli/lib/reporter`)
-const resolveModuleExports = require(`../resolve-module-exports`)
+const { resolveModuleExports } = require(`../resolve-module-exports`)
 let resolver
 
 describe(`Resolve module exports`, () => {
diff --git a/packages/gatsby/src/bootstrap/load-plugins/__tests__/validate.js b/packages/gatsby/src/bootstrap/load-plugins/__tests__/validate.js
index 1d08d7fed15cd..c118e78575c49 100644
--- a/packages/gatsby/src/bootstrap/load-plugins/__tests__/validate.js
+++ b/packages/gatsby/src/bootstrap/load-plugins/__tests__/validate.js
@@ -41,7 +41,7 @@ describe(`collatePluginAPIs`, () => {
   }
 
   beforeEach(() => {
-    const resolveModuleExports = require(`../../resolve-module-exports`)
+    const { resolveModuleExports } = require(`../../resolve-module-exports`)
     resolveModuleExports(MOCK_RESULTS)
   })
 
diff --git a/packages/gatsby/src/bootstrap/load-plugins/validate.js b/packages/gatsby/src/bootstrap/load-plugins/validate.js
index 4fdaffba5392c..fd9c8bc433e99 100644
--- a/packages/gatsby/src/bootstrap/load-plugins/validate.js
+++ b/packages/gatsby/src/bootstrap/load-plugins/validate.js
@@ -3,7 +3,7 @@ const semver = require(`semver`)
 const stringSimilarity = require(`string-similarity`)
 const { version: gatsbyVersion } = require(`gatsby/package.json`)
 const reporter = require(`gatsby-cli/lib/reporter`)
-const resolveModuleExports = require(`../resolve-module-exports`)
+const { resolveModuleExports } = require(`../resolve-module-exports`)
 const { getLatestAPIs } = require(`../../utils/get-latest-apis`)
 
 const getGatsbyUpgradeVersion = entries =>
diff --git a/packages/gatsby/src/bootstrap/resolve-module-exports.js b/packages/gatsby/src/bootstrap/resolve-module-exports.ts
similarity index 84%
rename from packages/gatsby/src/bootstrap/resolve-module-exports.js
rename to packages/gatsby/src/bootstrap/resolve-module-exports.ts
index 8d141291c5007..3e5611f02bda9 100644
--- a/packages/gatsby/src/bootstrap/resolve-module-exports.js
+++ b/packages/gatsby/src/bootstrap/resolve-module-exports.ts
@@ -1,16 +1,18 @@
-// @flow
 import fs from "fs"
 import traverse from "@babel/traverse"
 import get from "lodash/get"
-import { codeFrameColumns } from "@babel/code-frame"
+import { codeFrameColumns, SourceLocation } from "@babel/code-frame"
 import { babelParseToAst } from "../utils/babel-parse-to-ast"
 import report from "gatsby-cli/lib/reporter"
 
 import { testRequireError } from "../utils/test-require-error"
 
-const staticallyAnalyzeExports = (modulePath, resolver = require.resolve) => {
-  let absPath
-  const exportNames = []
+const staticallyAnalyzeExports = (
+  modulePath: string,
+  resolver = require.resolve
+): string[] => {
+  let absPath: string | undefined
+  const exportNames: string[] = []
 
   try {
     absPath = resolver(modulePath)
@@ -28,7 +30,7 @@ const staticallyAnalyzeExports = (modulePath, resolver = require.resolve) => {
       const codeFrame = codeFrameColumns(
         code,
         {
-          start: err.loc,
+          start: ((err as unknown) as { loc: SourceLocation["start"] }).loc,
         },
         {
           highlightCode: true,
@@ -50,7 +52,7 @@ const staticallyAnalyzeExports = (modulePath, resolver = require.resolve) => {
   // extract names of exports from file
   traverse(ast, {
     // Check if the file is using ES6 imports
-    ImportDeclaration: function ImportDeclaration(astPath) {
+    ImportDeclaration: function ImportDeclaration() {
       isES6 = true
     },
 
@@ -59,8 +61,8 @@ const staticallyAnalyzeExports = (modulePath, resolver = require.resolve) => {
 
       // get foo from `export const foo = bar`
       if (
-        get(astPath, `node.declaration.type`) === `VariableDeclaration` &&
-        get(astPath, `node.declaration.declarations[0].id.name`)
+        declaration?.type === `VariableDeclaration` &&
+        declaration.declarations[0]?.id.type === `Identifier`
       ) {
         isES6 = true
         exportNames.push(declaration.declarations[0].id.name)
@@ -68,8 +70,8 @@ const staticallyAnalyzeExports = (modulePath, resolver = require.resolve) => {
 
       // get foo from `export function foo()`
       if (
-        get(astPath, `node.declaration.type`) === `FunctionDeclaration` &&
-        get(astPath, `node.declaration.id.name`)
+        declaration?.type === `FunctionDeclaration` &&
+        declaration.id?.type === `Identifier`
       ) {
         isES6 = true
         exportNames.push(declaration.id.name)
@@ -139,16 +141,16 @@ https://gatsby.dev/no-mixed-modules
  *
  * Returns [] for invalid paths and modules without exports.
  *
- * @param {string} modulePath
- * @param {string} mode
- * @param {function} resolver
+ * @param modulePath
+ * @param mode
+ * @param resolver
  */
-module.exports = (
-  modulePath,
+export const resolveModuleExports = (
+  modulePath: string,
   { mode = `analysis`, resolver = require.resolve } = {}
-) => {
+): string[] => {
   if (mode === `require`) {
-    let absPath
+    let absPath: string | undefined
     try {
       absPath = resolver(modulePath)
       return Object.keys(require(modulePath)).filter(