diff --git a/packages/assets-registry/registry.js b/packages/assets-registry/registry.js
index 435bd519411f..d193d3af1c87 100644
--- a/packages/assets-registry/registry.js
+++ b/packages/assets-registry/registry.js
@@ -14,16 +14,16 @@
 export type AssetDestPathResolver = 'android' | 'generic';
 
 export type PackagerAsset = {
-  +__packager_asset: boolean,
-  +fileSystemLocation: string,
-  +httpServerLocation: string,
-  +width: ?number,
-  +height: ?number,
-  +scales: Array<number>,
-  +hash: string,
-  +name: string,
-  +type: string,
-  +resolver?: AssetDestPathResolver,
+  readonly __packager_asset: boolean,
+  readonly fileSystemLocation: string,
+  readonly httpServerLocation: string,
+  readonly width: ?number,
+  readonly height: ?number,
+  readonly scales: Array<number>,
+  readonly hash: string,
+  readonly name: string,
+  readonly type: string,
+  readonly resolver?: AssetDestPathResolver,
   ...
 };
 */
diff --git a/packages/dev-middleware/src/inspector-proxy/types.js b/packages/dev-middleware/src/inspector-proxy/types.js
index 8d95b8554517..89838f2d11d0 100644
--- a/packages/dev-middleware/src/inspector-proxy/types.js
+++ b/packages/dev-middleware/src/inspector-proxy/types.js
@@ -162,5 +162,5 @@ export type DeepReadOnly<T> =
   T extends ReadonlyArray<infer V>
     ? ReadonlyArray<DeepReadOnly<V>>
     : T extends {...}
-      ? {+[K in keyof T]: DeepReadOnly<T[K]>}
+      ? {readonly [K in keyof T]: DeepReadOnly<T[K]>}
       : T;
diff --git a/packages/react-native/Libraries/Animated/createAnimatedComponent.js b/packages/react-native/Libraries/Animated/createAnimatedComponent.js
index 435aea045ce6..b6b3953b429d 100644
--- a/packages/react-native/Libraries/Animated/createAnimatedComponent.js
+++ b/packages/react-native/Libraries/Animated/createAnimatedComponent.js
@@ -51,7 +51,7 @@ export type WithAnimatedValue<out T> = T extends Builtin | Nullable
     : T extends ReadonlyArray<infer P>
       ? ReadonlyArray<WithAnimatedValue<P>>
       : T extends {...}
-        ? {+[K in keyof T]: WithAnimatedValue<T[K]>}
+        ? {readonly [K in keyof T]: WithAnimatedValue<T[K]>}
         : T;
 
 type NonAnimatedProps =
diff --git a/packages/react-native/scripts/ios-prebuild/hermes.js b/packages/react-native/scripts/ios-prebuild/hermes.js
index 94f7883b49b1..eb3df6314352 100644
--- a/packages/react-native/scripts/ios-prebuild/hermes.js
+++ b/packages/react-native/scripts/ios-prebuild/hermes.js
@@ -133,8 +133,8 @@ type HermesEngineSourceType =
 */
 
 const HermesEngineSourceTypes /*:{
-  +DOWNLOAD_PREBUILD_TARBALL: "download_prebuild_tarball",
-  +LOCAL_PREBUILT_TARBALL: "local_prebuilt_tarball"
+  readonly DOWNLOAD_PREBUILD_TARBALL: "download_prebuild_tarball",
+  readonly LOCAL_PREBUILT_TARBALL: "local_prebuilt_tarball"
 } */ = {
   LOCAL_PREBUILT_TARBALL: 'local_prebuilt_tarball',
   DOWNLOAD_PREBUILD_TARBALL: 'download_prebuild_tarball',
diff --git a/packages/react-native/scripts/ios-prebuild/reactNativeDependencies.js b/packages/react-native/scripts/ios-prebuild/reactNativeDependencies.js
index 7bd799d83b8e..f497338bef8b 100644
--- a/packages/react-native/scripts/ios-prebuild/reactNativeDependencies.js
+++ b/packages/react-native/scripts/ios-prebuild/reactNativeDependencies.js
@@ -124,8 +124,8 @@ type ReactNativeDependenciesEngineSourceType =
 */
 
 const ReactNativeDependenciesEngineSourceTypes /*: {
-  +DOWNLOAD_PREBUILD_TARBALL: "download_prebuild_tarball",
-  +DOWNLOAD_PREBUILT_NIGHTLY_TARBALL: "download_prebuilt_nightly_tarball"
+  readonly DOWNLOAD_PREBUILD_TARBALL: "download_prebuild_tarball",
+  readonly DOWNLOAD_PREBUILT_NIGHTLY_TARBALL: "download_prebuilt_nightly_tarball"
 } */ = {
   DOWNLOAD_PREBUILD_TARBALL: 'download_prebuild_tarball',
   DOWNLOAD_PREBUILT_NIGHTLY_TARBALL: 'download_prebuilt_nightly_tarball',
diff --git a/private/core-cli-utils/src/private/app.js b/private/core-cli-utils/src/private/app.js
index afb792541432..21e9ea297dcc 100644
--- a/private/core-cli-utils/src/private/app.js
+++ b/private/core-cli-utils/src/private/app.js
@@ -27,7 +27,7 @@ type BundlerOptions = {
   config?: string,
   // Typically index.{ios,android}.js
   entryFile: string,
-  +platform: 'ios' | 'android' | string,
+  readonly platform: 'ios' | 'android' | string,
   dev: boolean,
   // Metro built main bundle
   outputJsBundle: string,
@@ -58,12 +58,12 @@ type HermesConfig = {
 };
 
 type BundlerWatch = {
-  +mode: 'watch',
+  readonly mode: 'watch',
   callback?: (metro: ExecaPromise) => void,
 };
 
 type BundlerBuild = {
-  +mode: 'bundle',
+  readonly mode: 'bundle',
 };
 
 type Bundler = BundlerWatch | BundlerBuild;