diff --git a/.flowconfig b/.flowconfig
index 0563c1419..028f9aaac 100644
--- a/.flowconfig
+++ b/.flowconfig
@@ -27,7 +27,7 @@ esproposal.export_star_as=enable
 esproposal.optional_chaining=enable
 esproposal.nullish_coalescing=enable
 module.name_mapper='^[./a-zA-Z0-9$_-]+\.\(bmp\|gif\|jpg\|jpeg\|png\|psd\|svg\|webp\|m4v\|mov\|mp4\|mpeg\|mpg\|webm\|aac\|aiff\|caf\|m4a\|mp3\|wav\|html\|pdf\)$' -> 'RelativeImageStub'
-module.name_mapper='types' -> '<PROJECT_ROOT>/types/index.js'
+module.name_mapper='^types' -> '<PROJECT_ROOT>/types/index.js'
 
 suppress_type=$FlowIssue
 suppress_type=$FlowFixMe
diff --git a/packages/cli/src/commands/doctor/checkInstallation.js b/packages/cli/src/commands/doctor/checkInstallation.js
index 1a42a7f79..6a9647f96 100644
--- a/packages/cli/src/commands/doctor/checkInstallation.js
+++ b/packages/cli/src/commands/doctor/checkInstallation.js
@@ -1,3 +1,4 @@
+// @flow
 import semver from 'semver';
 import commandExists from 'command-exists';
 
@@ -6,7 +7,7 @@ const PACKAGE_MANAGERS = {
   NPM: 'NPM',
 };
 
-const isSoftwareInstalled = async command => {
+const isSoftwareInstalled = async (command: string) => {
   try {
     await commandExists(command);
 
@@ -16,7 +17,13 @@ const isSoftwareInstalled = async command => {
   }
 };
 
-const doesSoftwareNeedToBeFixed = ({version, versionRange}) =>
+const doesSoftwareNeedToBeFixed = ({
+  version,
+  versionRange,
+}: {
+  version: string,
+  versionRange: string,
+}) =>
   version === 'Not Found' ||
   !semver.satisfies(semver.coerce(version), versionRange);
 
diff --git a/packages/cli/src/commands/doctor/doctor.js b/packages/cli/src/commands/doctor/doctor.js
index 3cf14324e..474bd6e43 100644
--- a/packages/cli/src/commands/doctor/doctor.js
+++ b/packages/cli/src/commands/doctor/doctor.js
@@ -1,3 +1,4 @@
+// @flow
 import chalk from 'chalk';
 import envinfo from 'envinfo';
 import {logger} from '@react-native-community/cli-tools';
@@ -5,6 +6,8 @@ import {getHealthchecks, HEALTHCHECK_TYPES} from './healthchecks';
 import {getLoader} from '../../tools/loader';
 import printFixOptions, {KEYS} from './printFixOptions';
 import runAutomaticFix, {AUTOMATIC_FIX_LEVELS} from './runAutomaticFix';
+import type {ConfigT} from 'types';
+import type {HealthCheckInterface} from './types';
 
 const printCategory = ({label, key}) => {
   if (key > 0) {
@@ -14,7 +17,15 @@ const printCategory = ({label, key}) => {
   logger.log(chalk.dim(label));
 };
 
-const printIssue = ({label, needsToBeFixed, isRequired}) => {
+const printIssue = ({
+  label,
+  needsToBeFixed,
+  isRequired,
+}: {
+  label: string,
+  needsToBeFixed: boolean,
+  isRequired: boolean,
+}) => {
   const symbol = needsToBeFixed
     ? isRequired
       ? chalk.red('✖')
@@ -29,7 +40,16 @@ const printOverallStats = ({errors, warnings}) => {
   logger.log(`${chalk.bold('Warnings:')} ${warnings}`);
 };
 
-export default (async function runDoctor(argv, ctx, options) {
+type FlagsT = {
+  fix: boolean | void,
+  contributor: boolean | void,
+};
+
+export default (async function runDoctor(
+  argv: Array<string>,
+  ctx: ConfigT,
+  options: FlagsT,
+) {
   const Loader = getLoader();
   const loader = new Loader();
 
@@ -48,7 +68,13 @@ export default (async function runDoctor(argv, ctx, options) {
     ),
   );
 
-  const iterateOverHealthChecks = async ({label, healthchecks}) => ({
+  const iterateOverHealthChecks = async ({
+    label,
+    healthchecks,
+  }: {
+    label: string,
+    healthchecks: Array<HealthCheckInterface>,
+  }) => ({
     label,
     healthchecks: (await Promise.all(
       healthchecks.map(async healthcheck => {
@@ -56,9 +82,9 @@ export default (async function runDoctor(argv, ctx, options) {
           return;
         }
 
-        const {needsToBeFixed} = healthcheck.getDiagnostics
-          ? healthcheck.getDiagnostics(environmentInfo)
-          : await healthcheck.getDiagnosticsAsync(environmentInfo);
+        const {needsToBeFixed} = await healthcheck.getDiagnostics(
+          environmentInfo,
+        );
 
         // Assume that it's required unless specified otherwise
         const isRequired = healthcheck.isRequired !== false;
@@ -66,7 +92,7 @@ export default (async function runDoctor(argv, ctx, options) {
 
         return {
           label: healthcheck.label,
-          needsToBeFixed,
+          needsToBeFixed: Boolean(needsToBeFixed),
           runAutomaticFix: healthcheck.runAutomaticFix,
           isRequired,
           type: needsToBeFixed
@@ -87,6 +113,7 @@ export default (async function runDoctor(argv, ctx, options) {
     );
 
   const iterateOverCategories = categories =>
+    // $FlowFixMe - bad Object.values typings
     Promise.all(categories.map(iterateOverHealthChecks));
 
   const healthchecksPerCategory = await iterateOverCategories(
@@ -129,6 +156,7 @@ export default (async function runDoctor(argv, ctx, options) {
   }
 
   const onKeyPress = async key => {
+    // $FlowFixMe
     process.stdin.setRawMode(false);
     process.stdin.removeAllListeners('data');
 
diff --git a/packages/cli/src/commands/doctor/healthchecks/androidHomeEnvVariable.js b/packages/cli/src/commands/doctor/healthchecks/androidHomeEnvVariable.js
index 92902223e..410b9855d 100644
--- a/packages/cli/src/commands/doctor/healthchecks/androidHomeEnvVariable.js
+++ b/packages/cli/src/commands/doctor/healthchecks/androidHomeEnvVariable.js
@@ -1,5 +1,8 @@
+// @flow
 import chalk from 'chalk';
+import Ora from 'ora';
 import {logManualInstallation} from './common';
+import type {HealthCheckInterface} from '../types';
 
 // List of answers on how to set `ANDROID_HOME` for each platform
 const URLS = {
@@ -10,12 +13,12 @@ const URLS = {
 
 const label = 'ANDROID_HOME';
 
-export default {
+export default ({
   label,
-  getDiagnostics: () => ({
+  getDiagnostics: async () => ({
     needsToBeFixed: !process.env.ANDROID_HOME,
   }),
-  runAutomaticFix: async ({loader}) => {
+  runAutomaticFix: async ({loader}: {loader: typeof Ora}) => {
     loader.info();
 
     logManualInstallation({
@@ -24,4 +27,4 @@ export default {
       )}.`,
     });
   },
-};
+}: HealthCheckInterface);
diff --git a/packages/cli/src/commands/doctor/healthchecks/androidNDK.js b/packages/cli/src/commands/doctor/healthchecks/androidNDK.js
index 0f07e58ea..d3481e1fe 100644
--- a/packages/cli/src/commands/doctor/healthchecks/androidNDK.js
+++ b/packages/cli/src/commands/doctor/healthchecks/androidNDK.js
@@ -1,17 +1,26 @@
+// @flow
 import chalk from 'chalk';
+import Ora from 'ora';
 import {logManualInstallation} from './common';
 import versionRanges from '../versionRanges';
 import {doesSoftwareNeedToBeFixed} from '../checkInstallation';
+import type {EnvironmentInfo, HealthCheckInterface} from '../types';
 
-export default {
+export default ({
   label: 'Android NDK',
-  getDiagnosticsAsync: async ({SDKs}) => ({
+  getDiagnostics: async ({SDKs}: EnvironmentInfo) => ({
     needsToBeFixed: doesSoftwareNeedToBeFixed({
       version: SDKs['Android SDK']['Android NDK'],
       versionRange: versionRanges.ANDROID_NDK,
     }),
   }),
-  runAutomaticFix: async ({loader, environmentInfo}) => {
+  runAutomaticFix: async ({
+    loader,
+    environmentInfo,
+  }: {
+    loader: typeof Ora,
+    environmentInfo: EnvironmentInfo,
+  }) => {
     const version = environmentInfo.SDKs['Android SDK']['Android NDK'];
     const isNDKInstalled = version !== 'Not Found';
 
@@ -30,4 +39,4 @@ export default {
       url: 'https://developer.android.com/ndk/downloads',
     });
   },
-};
+}: HealthCheckInterface);
diff --git a/packages/cli/src/commands/doctor/healthchecks/androidSDK.js b/packages/cli/src/commands/doctor/healthchecks/androidSDK.js
index 7707a9d87..c82e0eaf5 100644
--- a/packages/cli/src/commands/doctor/healthchecks/androidSDK.js
+++ b/packages/cli/src/commands/doctor/healthchecks/androidSDK.js
@@ -1,16 +1,19 @@
+// @flow
 import chalk from 'chalk';
+import Ora from 'ora';
 import {logManualInstallation} from './common';
 import versionRanges from '../versionRanges';
 import {doesSoftwareNeedToBeFixed} from '../checkInstallation';
 import execa from 'execa';
+import type {EnvironmentInfo, HealthCheckInterface} from '../types';
 
 const installMessage = `Read more about how to update Android SDK at ${chalk.dim(
   'https://developer.android.com/studio',
 )}`;
 
-export default {
+export default ({
   label: 'Android SDK',
-  getDiagnosticsAsync: async ({SDKs}) => {
+  getDiagnostics: async ({SDKs}: EnvironmentInfo) => {
     let sdks = SDKs['Android SDK'];
 
     // This is a workaround for envinfo's Android SDK check not working on
@@ -18,6 +21,7 @@ export default {
     // See the PR: https://github.com/tabrindle/envinfo/pull/119
     if (sdks === 'Not Found' && process.platform !== 'darwin') {
       try {
+        // $FlowFixMe bad execa types
         const {stdout} = await execa(
           process.env.ANDROID_HOME
             ? `${process.env.ANDROID_HOME}/tools/bin/sdkmanager`
@@ -29,7 +33,9 @@ export default {
         const regex = /build-tools;([\d|.]+)[\S\s]/g;
         let match = null;
         while ((match = regex.exec(stdout)) !== null) {
-          matches.push(match[1]);
+          if (match) {
+            matches.push(match[1]);
+          }
         }
         if (matches.length > 0) {
           sdks = {
@@ -42,13 +48,20 @@ export default {
     return {
       needsToBeFixed:
         (sdks === 'Not Found' && installMessage) ||
-        doesSoftwareNeedToBeFixed({
-          version: sdks['Build Tools'][0],
-          versionRange: versionRanges.ANDROID_NDK,
-        }),
+        (sdks !== 'Not Found' &&
+          doesSoftwareNeedToBeFixed({
+            version: sdks['Build Tools'][0],
+            versionRange: versionRanges.ANDROID_NDK,
+          })),
     };
   },
-  runAutomaticFix: async ({loader, environmentInfo}) => {
+  runAutomaticFix: async ({
+    loader,
+    environmentInfo,
+  }: {
+    loader: typeof Ora,
+    environmentInfo: EnvironmentInfo,
+  }) => {
     const version = environmentInfo.SDKs['Android SDK'][0];
     const isNDKInstalled = version !== 'Not Found';
 
@@ -65,4 +78,4 @@ export default {
       url: 'https://facebook.github.io/react-native/docs/getting-started',
     });
   },
-};
+}: HealthCheckInterface);
diff --git a/packages/cli/src/commands/doctor/healthchecks/cocoaPods.js b/packages/cli/src/commands/doctor/healthchecks/cocoaPods.js
index dd8597b99..5644278c6 100644
--- a/packages/cli/src/commands/doctor/healthchecks/cocoaPods.js
+++ b/packages/cli/src/commands/doctor/healthchecks/cocoaPods.js
@@ -1,10 +1,12 @@
+// @flow
 import {isSoftwareInstalled} from '../checkInstallation';
 import {installCocoaPods} from '../../../tools/installPods';
+import {type HealthCheckInterface} from '../types';
 
-export default {
+export default ({
   label: 'CocoaPods',
-  getDiagnosticsAsync: async () => ({
+  getDiagnostics: async () => ({
     needsToBeFixed: !(await isSoftwareInstalled('pod')),
   }),
   runAutomaticFix: async ({loader}) => await installCocoaPods(loader),
-};
+}: HealthCheckInterface);
diff --git a/packages/cli/src/commands/doctor/healthchecks/common.js b/packages/cli/src/commands/doctor/healthchecks/common.js
index cc48db2c5..1bce843c3 100644
--- a/packages/cli/src/commands/doctor/healthchecks/common.js
+++ b/packages/cli/src/commands/doctor/healthchecks/common.js
@@ -1,10 +1,21 @@
+// @flow
 import logger from '@react-native-community/cli-tools/build/logger';
 import chalk from 'chalk';
 
 // Space is necessary to keep correct ordering on screen
 const logMessage = message => logger.log(`   ${message}`);
 
-const logManualInstallation = ({healthcheck, url, command, message}) => {
+const logManualInstallation = ({
+  healthcheck = '',
+  url,
+  command,
+  message,
+}: {
+  healthcheck?: string,
+  url?: string,
+  command?: string,
+  message?: string,
+}) => {
   if (message) {
     return logMessage(message);
   }
diff --git a/packages/cli/src/commands/doctor/healthchecks/index.js b/packages/cli/src/commands/doctor/healthchecks/index.js
index 19d49a93f..c95ddf644 100644
--- a/packages/cli/src/commands/doctor/healthchecks/index.js
+++ b/packages/cli/src/commands/doctor/healthchecks/index.js
@@ -1,3 +1,4 @@
+// @flow
 import nodeJS from './nodeJS';
 import {yarn, npm} from './packageManagers';
 import watchman from './watchman';
@@ -13,7 +14,12 @@ export const HEALTHCHECK_TYPES = {
   WARNING: 'WARNING',
 };
 
-export const getHealthchecks = ({contributor}) => ({
+type Options = {
+  fix: boolean | void,
+  contributor: boolean | void,
+};
+
+export const getHealthchecks = ({contributor}: Options) => ({
   common: {
     label: 'Common',
     healthchecks: [
@@ -25,7 +31,6 @@ export const getHealthchecks = ({contributor}) => ({
   },
   android: {
     label: 'Android',
-    // TODO: Android NDK should be shown only with a special flag
     healthchecks: [
       androidHomeEnvVariable,
       androidSDK,
diff --git a/packages/cli/src/commands/doctor/healthchecks/iosDeploy.js b/packages/cli/src/commands/doctor/healthchecks/iosDeploy.js
index 37bec8bb4..b4a8e9aed 100644
--- a/packages/cli/src/commands/doctor/healthchecks/iosDeploy.js
+++ b/packages/cli/src/commands/doctor/healthchecks/iosDeploy.js
@@ -1,7 +1,10 @@
+// @flow
 import execa from 'execa';
+import Ora from 'ora';
 import {isSoftwareInstalled, PACKAGE_MANAGERS} from '../checkInstallation';
 import {packageManager} from './packageManagers';
 import {logManualInstallation} from './common';
+import type {HealthCheckInterface} from '../types';
 
 const getInstallationCommand = () => {
   if (packageManager === PACKAGE_MANAGERS.YARN) {
@@ -15,13 +18,13 @@ const getInstallationCommand = () => {
   return undefined;
 };
 
-export default {
+export default ({
   label: 'ios-deploy',
   isRequired: false,
-  getDiagnosticsAsync: async () => ({
+  getDiagnostics: async () => ({
     needsToBeFixed: !(await isSoftwareInstalled('ios-deploy')),
   }),
-  runAutomaticFix: async ({loader}) => {
+  runAutomaticFix: async ({loader}: {loader: typeof Ora}) => {
     const installationCommand = getInstallationCommand();
 
     // This means that we couldn't "guess" the package manager
@@ -33,6 +36,7 @@ export default {
         healthcheck: 'ios-deploy',
         url: 'https://github.com/ios-control/ios-deploy#readme',
       });
+      return;
     }
 
     try {
@@ -51,4 +55,4 @@ export default {
       });
     }
   },
-};
+}: HealthCheckInterface);
diff --git a/packages/cli/src/commands/doctor/healthchecks/nodeJS.js b/packages/cli/src/commands/doctor/healthchecks/nodeJS.js
index bae6bc910..a4dfdd8eb 100644
--- a/packages/cli/src/commands/doctor/healthchecks/nodeJS.js
+++ b/packages/cli/src/commands/doctor/healthchecks/nodeJS.js
@@ -1,17 +1,20 @@
+// @flow
+import Ora from 'ora';
 import versionRanges from '../versionRanges';
 import {doesSoftwareNeedToBeFixed} from '../checkInstallation';
 import {logManualInstallation} from './common';
+import type {EnvironmentInfo, HealthCheckInterface} from '../types';
 
-export default {
+export default ({
   label: 'Node.js',
-  getDiagnostics: ({Binaries}) => ({
+  getDiagnostics: async ({Binaries}: EnvironmentInfo) => ({
     version: Binaries.Node.version,
     needsToBeFixed: doesSoftwareNeedToBeFixed({
       version: Binaries.Node.version,
       versionRange: versionRanges.NODE_JS,
     }),
   }),
-  runAutomaticFix: async ({loader}) => {
+  runAutomaticFix: async ({loader}: {loader: typeof Ora}) => {
     loader.fail();
 
     logManualInstallation({
@@ -19,4 +22,4 @@ export default {
       url: 'https://nodejs.org/en/download/',
     });
   },
-};
+}: HealthCheckInterface);
diff --git a/packages/cli/src/commands/doctor/healthchecks/packageManagers.js b/packages/cli/src/commands/doctor/healthchecks/packageManagers.js
index d14a917b3..92433c7ad 100644
--- a/packages/cli/src/commands/doctor/healthchecks/packageManagers.js
+++ b/packages/cli/src/commands/doctor/healthchecks/packageManagers.js
@@ -1,10 +1,13 @@
+// @flow
 import fs from 'fs';
+import Ora from 'ora';
 import versionRanges from '../versionRanges';
 import {
   PACKAGE_MANAGERS,
   doesSoftwareNeedToBeFixed,
 } from '../checkInstallation';
 import {install} from '../../../tools/install';
+import type {EnvironmentInfo, HealthCheckInterface} from '../types';
 
 const packageManager = (() => {
   if (fs.existsSync('yarn.lock')) {
@@ -18,9 +21,9 @@ const packageManager = (() => {
   return undefined;
 })();
 
-const yarn = {
+const yarn: HealthCheckInterface = {
   label: 'yarn',
-  getDiagnostics: ({Binaries}) => ({
+  getDiagnostics: async ({Binaries}: EnvironmentInfo) => ({
     version: Binaries.Node.version,
     needsToBeFixed: doesSoftwareNeedToBeFixed({
       version: Binaries.Yarn.version,
@@ -31,13 +34,13 @@ const yarn = {
   // or if we can't identify that the user uses yarn or npm
   visible:
     packageManager === PACKAGE_MANAGERS.YARN || packageManager === undefined,
-  runAutomaticFix: async ({loader}) =>
+  runAutomaticFix: async ({loader}: typeof Ora) =>
     await install('yarn', 'https://yarnpkg.com/docs/install', loader),
 };
 
-const npm = {
+const npm: HealthCheckInterface = {
   label: 'npm',
-  getDiagnostics: ({Binaries}) => ({
+  getDiagnostics: async ({Binaries}: EnvironmentInfo) => ({
     needsToBeFixed: doesSoftwareNeedToBeFixed({
       version: Binaries.npm.version,
       versionRange: versionRanges.NPM,
@@ -47,7 +50,7 @@ const npm = {
   // or if we can't identify that the user uses yarn or npm
   visible:
     packageManager === PACKAGE_MANAGERS.NPM || packageManager === undefined,
-  runAutomaticFix: async ({loader}) =>
+  runAutomaticFix: async ({loader}: typeof Ora) =>
     await install('node', 'https://nodejs.org/', loader),
 };
 
diff --git a/packages/cli/src/commands/doctor/healthchecks/watchman.js b/packages/cli/src/commands/doctor/healthchecks/watchman.js
index e32967b99..798708a78 100644
--- a/packages/cli/src/commands/doctor/healthchecks/watchman.js
+++ b/packages/cli/src/commands/doctor/healthchecks/watchman.js
@@ -1,16 +1,19 @@
+// @flow
+import Ora from 'ora';
 import versionRanges from '../versionRanges';
 import {doesSoftwareNeedToBeFixed} from '../checkInstallation';
 import {install} from '../../../tools/install';
+import type {EnvironmentInfo} from '../types';
 
 export default {
   label: 'Watchman',
-  getDiagnostics: ({Binaries}) => ({
+  getDiagnostics: ({Binaries}: EnvironmentInfo) => ({
     needsToBeFixed: doesSoftwareNeedToBeFixed({
       version: Binaries.Watchman.version,
       versionRange: versionRanges.WATCHMAN,
     }),
   }),
-  runAutomaticFix: async ({loader}) =>
+  runAutomaticFix: async ({loader}: typeof Ora) =>
     await install(
       'watchman',
       'https://facebook.github.io/watchman/docs/install.html',
diff --git a/packages/cli/src/commands/doctor/healthchecks/xcode.js b/packages/cli/src/commands/doctor/healthchecks/xcode.js
index c16900886..74ac04a7c 100644
--- a/packages/cli/src/commands/doctor/healthchecks/xcode.js
+++ b/packages/cli/src/commands/doctor/healthchecks/xcode.js
@@ -1,16 +1,19 @@
+// @flow
+import Ora from 'ora';
 import versionRanges from '../versionRanges';
 import {doesSoftwareNeedToBeFixed} from '../checkInstallation';
 import {logManualInstallation} from './common';
+import type {EnvironmentInfo, HealthCheckInterface} from '../types';
 
-export default {
+export default ({
   label: 'Xcode',
-  getDiagnostics: ({IDEs}) => ({
+  getDiagnostics: async ({IDEs}: EnvironmentInfo) => ({
     needsToBeFixed: doesSoftwareNeedToBeFixed({
       version: IDEs.Xcode.version.split('/')[0],
       versionRange: versionRanges.XCODE,
     }),
   }),
-  runAutomaticFix: ({loader}) => {
+  runAutomaticFix: async ({loader}: {loader: typeof Ora}) => {
     loader.info();
 
     logManualInstallation({
@@ -18,4 +21,4 @@ export default {
       url: 'https://developer.apple.com/xcode/',
     });
   },
-};
+}: HealthCheckInterface);
diff --git a/packages/cli/src/commands/doctor/printFixOptions.js b/packages/cli/src/commands/doctor/printFixOptions.js
index ecd589d7b..9134f8c0f 100644
--- a/packages/cli/src/commands/doctor/printFixOptions.js
+++ b/packages/cli/src/commands/doctor/printFixOptions.js
@@ -1,5 +1,7 @@
+// @flow
 import chalk from 'chalk';
 import {logger} from '@react-native-community/cli-tools';
+
 const KEYS = {
   FIX_ALL_ISSUES: 'f',
   FIX_ERRORS: 'e',
@@ -28,9 +30,10 @@ const printOptions = () => {
 };
 
 export {KEYS};
-export default ({onKeyPress}) => {
+export default ({onKeyPress}: {onKeyPress: any}) => {
   printOptions();
 
+  // $FlowFixMe
   process.stdin.setRawMode(true);
   process.stdin.resume();
   process.stdin.setEncoding('utf8');
diff --git a/packages/cli/src/commands/doctor/runAutomaticFix.js b/packages/cli/src/commands/doctor/runAutomaticFix.js
index e16731ae2..f954dd9b7 100644
--- a/packages/cli/src/commands/doctor/runAutomaticFix.js
+++ b/packages/cli/src/commands/doctor/runAutomaticFix.js
@@ -1,7 +1,9 @@
+// @flow
 import chalk from 'chalk';
 import ora from 'ora';
 import logger from '../../tools/logger';
 import {HEALTHCHECK_TYPES} from './healthchecks';
+import type {EnvironmentInfo} from './types';
 
 const AUTOMATIC_FIX_LEVELS = {
   ALL_ISSUES: 'ALL_ISSUES',
@@ -16,9 +18,17 @@ export default async ({
   stats,
   loader,
   environmentInfo,
+}: {
+  healthchecks: any,
+  automaticFixLevel: $Values<typeof AUTOMATIC_FIX_LEVELS>,
+  stats: {errors: any, warnings: any},
+  loader: typeof ora,
+  environmentInfo: EnvironmentInfo,
 }) => {
   // Remove the fix options from screen
+  // $FlowFixMe
   process.stdout.moveCursor(0, -6);
+  // $FlowFixMe
   process.stdout.clearScreenDown();
 
   const totalIssuesBasedOnFixLevel = {
diff --git a/packages/cli/src/commands/doctor/types.js b/packages/cli/src/commands/doctor/types.js
new file mode 100644
index 000000000..3793e8d9b
--- /dev/null
+++ b/packages/cli/src/commands/doctor/types.js
@@ -0,0 +1,79 @@
+// @flow
+import Ora from 'ora';
+
+export type EnvironmentInfo = {
+  System: {
+    OS: string,
+    CPU: string,
+    Memory: string,
+    Shell: {
+      version: string,
+      path: string,
+    },
+  },
+  Binaries: {
+    Node: {
+      version: string,
+      path: string,
+    },
+    Yarn: {
+      version: string,
+      path: string,
+    },
+    npm: {
+      version: string,
+      path: string,
+    },
+    Watchman: {
+      version: string,
+      path: string,
+    },
+  },
+  SDKs: {
+    'iOS SDK': {
+      Platforms: string[],
+    },
+    'Android SDK': {
+      'API Levels': string[],
+      'Build Tools': string[],
+      'System Images': string[],
+      'Android NDK': string,
+    },
+  },
+  IDEs: {
+    'Android Studio': string,
+    Emacs: {
+      version: string,
+      path: string,
+    },
+    Nano: {
+      version: string,
+      path: string,
+    },
+    VSCode: {
+      version: string,
+      path: string,
+    },
+    Vim: {
+      version: string,
+      path: string,
+    },
+    Xcode: {
+      version: string,
+      path: string,
+    },
+  },
+};
+
+export type HealthCheckInterface = {
+  label: string,
+  visible?: boolean | void,
+  isRequired?: boolean,
+  getDiagnostics: (
+    environmentInfo: EnvironmentInfo,
+  ) => Promise<{version?: string, needsToBeFixed: boolean | string}>,
+  runAutomaticFix: (args: {
+    loader: typeof Ora,
+    environmentInfo: EnvironmentInfo,
+  }) => Promise<void> | void,
+};
diff --git a/packages/cli/src/commands/doctor/versionRanges.js b/packages/cli/src/commands/doctor/versionRanges.js
index d67496bd6..d1909f150 100644
--- a/packages/cli/src/commands/doctor/versionRanges.js
+++ b/packages/cli/src/commands/doctor/versionRanges.js
@@ -1,3 +1,4 @@
+// @flow
 export default {
   // Common
   NODE_JS: '>= 8.3',
diff --git a/packages/cli/src/tools/installPods.js b/packages/cli/src/tools/installPods.js
index b8f8853fe..6ce743dac 100644
--- a/packages/cli/src/tools/installPods.js
+++ b/packages/cli/src/tools/installPods.js
@@ -121,7 +121,7 @@ async function installPods({
       await execa('pod', ['--version']);
     } catch (e) {
       loader.info();
-      installCocoaPods(loader);
+      await installCocoaPods(loader);
     }
 
     if (shouldUpdatePods) {