diff --git a/packages/react-devtools-core/src/standalone.js b/packages/react-devtools-core/src/standalone.js
index 4a2ba8ff08e67..315b6bcaf936e 100644
--- a/packages/react-devtools-core/src/standalone.js
+++ b/packages/react-devtools-core/src/standalone.js
@@ -57,7 +57,7 @@ function hookNamesModuleLoaderFunction() {
   );
 }
 
-function setContentDOMNode(value: HTMLElement) {
+function setContentDOMNode(value: HTMLElement): typeof DevtoolsUI {
   node = value;
 
   // Save so we can restore the exact waiting message between sessions.
@@ -70,12 +70,14 @@ function setProjectRoots(value: Array<string>) {
   projectRoots = value;
 }
 
-function setStatusListener(value: StatusListener) {
+function setStatusListener(value: StatusListener): typeof DevtoolsUI {
   statusListener = value;
   return DevtoolsUI;
 }
 
-function setDisconnectedCallback(value: OnDisconnectedCallback) {
+function setDisconnectedCallback(
+  value: OnDisconnectedCallback,
+): typeof DevtoolsUI {
   disconnectedCallback = value;
   return DevtoolsUI;
 }
diff --git a/packages/react-is/src/ReactIs.js b/packages/react-is/src/ReactIs.js
index 26bf7e3c6b36d..8d383485daa49 100644
--- a/packages/react-is/src/ReactIs.js
+++ b/packages/react-is/src/ReactIs.js
@@ -26,7 +26,7 @@ import {
 } from 'shared/ReactSymbols';
 import isValidElementType from 'shared/isValidElementType';
 
-export function typeOf(object: any) {
+export function typeOf(object: any): mixed {
   if (typeof object === 'object' && object !== null) {
     const $$typeof = object.$$typeof;
     switch ($$typeof) {
diff --git a/packages/react-refresh/src/ReactFreshRuntime.js b/packages/react-refresh/src/ReactFreshRuntime.js
index 56af77a8e8584..00e7932ec401e 100644
--- a/packages/react-refresh/src/ReactFreshRuntime.js
+++ b/packages/react-refresh/src/ReactFreshRuntime.js
@@ -637,7 +637,12 @@ export function _getMountedRootCount(): number {
 //   'useState{[foo, setFoo]}(0)',
 //   () => [useCustomHook], /* Lazy to avoid triggering inline requires */
 // );
-export function createSignatureFunctionForTransform() {
+export function createSignatureFunctionForTransform(): <T>(
+  type: T,
+  key: string,
+  forceReset?: boolean,
+  getCustomHooks?: () => Array<Function>,
+) => T | void {
   if (__DEV__) {
     let savedType;
     let hasCustomHooks;
diff --git a/packages/react-server/src/ReactFlightHooks.js b/packages/react-server/src/ReactFlightHooks.js
index c2d319074e7f8..aa6358efcd4dc 100644
--- a/packages/react-server/src/ReactFlightHooks.js
+++ b/packages/react-server/src/ReactFlightHooks.js
@@ -122,12 +122,14 @@ function unsupportedRefresh(): void {
 
 let currentCache: Map<Function, mixed> | null = null;
 
-export function setCurrentCache(cache: Map<Function, mixed> | null) {
+export function setCurrentCache(
+  cache: Map<Function, mixed> | null,
+): Map<Function, mixed> | null {
   currentCache = cache;
   return currentCache;
 }
 
-export function getCurrentCache() {
+export function getCurrentCache(): Map<Function, mixed> | null {
   return currentCache;
 }
 
diff --git a/packages/use-sync-external-store/src/useSyncExternalStoreShim.js b/packages/use-sync-external-store/src/useSyncExternalStoreShim.js
index 82d944de1dd1d..73fcf26439010 100644
--- a/packages/use-sync-external-store/src/useSyncExternalStoreShim.js
+++ b/packages/use-sync-external-store/src/useSyncExternalStoreShim.js
@@ -14,5 +14,8 @@ import {useSyncExternalStore as builtInAPI} from 'react';
 
 const shim = isServerEnvironment ? server : client;
 
-export const useSyncExternalStore =
-  builtInAPI !== undefined ? ((builtInAPI: any): typeof shim) : shim;
+export const useSyncExternalStore: <T>(
+  subscribe: (() => void) => () => void,
+  getSnapshot: () => T,
+  getServerSnapshot?: () => T,
+) => T = builtInAPI !== undefined ? builtInAPI : shim;
diff --git a/scripts/flow/config/flowconfig b/scripts/flow/config/flowconfig
index d5330858f60c7..adc89ba407667 100644
--- a/scripts/flow/config/flowconfig
+++ b/scripts/flow/config/flowconfig
@@ -48,43 +48,43 @@ munge_underscores=false
 types_first=false
 
 well_formed_exports=true
-; well_formed_exports.includes=<PROJECT_ROOT>/packages/dom-event-testing-library
-; well_formed_exports.includes=<PROJECT_ROOT>/packages/eslint-plugin-react-hooks
-; well_formed_exports.includes=<PROJECT_ROOT>/packages/jest-mock-scheduler
-; well_formed_exports.includes=<PROJECT_ROOT>/packages/jest-react
+well_formed_exports.includes=<PROJECT_ROOT>/packages/dom-event-testing-library
+well_formed_exports.includes=<PROJECT_ROOT>/packages/eslint-plugin-react-hooks
+well_formed_exports.includes=<PROJECT_ROOT>/packages/jest-mock-scheduler
+well_formed_exports.includes=<PROJECT_ROOT>/packages/jest-react
 ; well_formed_exports.includes=<PROJECT_ROOT>/packages/react
-; well_formed_exports.includes=<PROJECT_ROOT>/packages/react-art
-; well_formed_exports.includes=<PROJECT_ROOT>/packages/react-cache
-; well_formed_exports.includes=<PROJECT_ROOT>/packages/react-client
-; well_formed_exports.includes=<PROJECT_ROOT>/packages/react-debug-tools
-; well_formed_exports.includes=<PROJECT_ROOT>/packages/react-devtools
-; well_formed_exports.includes=<PROJECT_ROOT>/packages/react-devtools-core
-; well_formed_exports.includes=<PROJECT_ROOT>/packages/react-devtools-extensions
-; well_formed_exports.includes=<PROJECT_ROOT>/packages/react-devtools-inline
+well_formed_exports.includes=<PROJECT_ROOT>/packages/react-art
+well_formed_exports.includes=<PROJECT_ROOT>/packages/react-cache
+well_formed_exports.includes=<PROJECT_ROOT>/packages/react-client
+well_formed_exports.includes=<PROJECT_ROOT>/packages/react-debug-tools
+well_formed_exports.includes=<PROJECT_ROOT>/packages/react-devtools
+well_formed_exports.includes=<PROJECT_ROOT>/packages/react-devtools-core
+well_formed_exports.includes=<PROJECT_ROOT>/packages/react-devtools-extensions
+well_formed_exports.includes=<PROJECT_ROOT>/packages/react-devtools-inline
 well_formed_exports.includes=<PROJECT_ROOT>/packages/react-devtools-shared
 well_formed_exports.includes=<PROJECT_ROOT>/packages/react-devtools-shell
 well_formed_exports.includes=<PROJECT_ROOT>/packages/react-devtools-timeline
 ; well_formed_exports.includes=<PROJECT_ROOT>/packages/react-dom
 ; well_formed_exports.includes=<PROJECT_ROOT>/packages/react-dom-bindings
-; well_formed_exports.includes=<PROJECT_ROOT>/packages/react-fetch
-; well_formed_exports.includes=<PROJECT_ROOT>/packages/react-fs
-; well_formed_exports.includes=<PROJECT_ROOT>/packages/react-interactions
-; well_formed_exports.includes=<PROJECT_ROOT>/packages/react-is
+well_formed_exports.includes=<PROJECT_ROOT>/packages/react-fetch
+well_formed_exports.includes=<PROJECT_ROOT>/packages/react-fs
+well_formed_exports.includes=<PROJECT_ROOT>/packages/react-interactions
+well_formed_exports.includes=<PROJECT_ROOT>/packages/react-is
 ; well_formed_exports.includes=<PROJECT_ROOT>/packages/react-native-renderer
-; well_formed_exports.includes=<PROJECT_ROOT>/packages/react-noop-renderer
-; well_formed_exports.includes=<PROJECT_ROOT>/packages/react-pg
+well_formed_exports.includes=<PROJECT_ROOT>/packages/react-noop-renderer
+well_formed_exports.includes=<PROJECT_ROOT>/packages/react-pg
 well_formed_exports.includes=<PROJECT_ROOT>/packages/react-reconciler
-; well_formed_exports.includes=<PROJECT_ROOT>/packages/react-refresh
-; well_formed_exports.includes=<PROJECT_ROOT>/packages/react-server
-; well_formed_exports.includes=<PROJECT_ROOT>/packages/react-server-dom-relay
-; well_formed_exports.includes=<PROJECT_ROOT>/packages/react-server-dom-webpack
-; well_formed_exports.includes=<PROJECT_ROOT>/packages/react-server-native-relay
-; well_formed_exports.includes=<PROJECT_ROOT>/packages/react-suspense-test-utils
+well_formed_exports.includes=<PROJECT_ROOT>/packages/react-refresh
+well_formed_exports.includes=<PROJECT_ROOT>/packages/react-server
+well_formed_exports.includes=<PROJECT_ROOT>/packages/react-server-dom-relay
+well_formed_exports.includes=<PROJECT_ROOT>/packages/react-server-dom-webpack
+well_formed_exports.includes=<PROJECT_ROOT>/packages/react-server-native-relay
+well_formed_exports.includes=<PROJECT_ROOT>/packages/react-suspense-test-utils
 ; well_formed_exports.includes=<PROJECT_ROOT>/packages/react-test-renderer
 well_formed_exports.includes=<PROJECT_ROOT>/packages/scheduler
 ; well_formed_exports.includes=<PROJECT_ROOT>/packages/shared
-; well_formed_exports.includes=<PROJECT_ROOT>/packages/use-subscription
-; well_formed_exports.includes=<PROJECT_ROOT>/packages/use-sync-external-store
+well_formed_exports.includes=<PROJECT_ROOT>/packages/use-subscription
+well_formed_exports.includes=<PROJECT_ROOT>/packages/use-sync-external-store
 
 # Substituted by createFlowConfig.js:
 %REACT_RENDERER_FLOW_OPTIONS%