diff --git a/packages/metro-file-map/src/watchers/FSEventsWatcher.js b/packages/metro-file-map/src/watchers/FSEventsWatcher.js
index c646f77fb..fe3e16bbe 100644
--- a/packages/metro-file-map/src/watchers/FSEventsWatcher.js
+++ b/packages/metro-file-map/src/watchers/FSEventsWatcher.js
@@ -9,24 +9,19 @@
  */
 
 import type {ChangeEventMetadata} from '../flow-types';
-import type {Stats} from 'fs';
 // $FlowFixMe[cannot-resolve-module] - Optional, Darwin only
 // $FlowFixMe[untyped-type-import]
 import type {FSEvents} from 'fsevents';
 
-import {isIncluded, typeFromStat} from './common';
+import {isIncluded, recReaddir, typeFromStat} from './common';
 // $FlowFixMe[untyped-import] - anymatch
 import anymatch from 'anymatch';
 import EventEmitter from 'events';
 import {promises as fsPromises} from 'fs';
 import * as path from 'path';
-// $FlowFixMe[untyped-import] - walker
-import walker from 'walker';
 
 const debug = require('debug')('Metro:FSEventsWatcher');
 
-type Matcher = typeof anymatch.Matcher;
-
 // $FlowFixMe[value-as-type]
 let fsevents: ?FSEvents = null;
 try {
@@ -54,7 +49,7 @@ type FsEventsWatcherEvent =
  */
 export default class FSEventsWatcher extends EventEmitter {
   +root: string;
-  +ignored: ?Matcher;
+  +ignored: ?RegExp;
   +glob: $ReadOnlyArray<string>;
   +dot: boolean;
   +doIgnore: (path: string) => boolean;
@@ -66,38 +61,10 @@ export default class FSEventsWatcher extends EventEmitter {
     return fsevents != null;
   }
 
-  static _normalizeProxy(
-    callback: (normalizedPath: string, stats: Stats) => void,
-  ): (filepath: string, stats: Stats) => void {
-    return (filepath: string, stats: Stats): void =>
-      callback(path.normalize(filepath), stats);
-  }
-
-  static _recReaddir(
-    dir: string,
-    dirCallback: (normalizedPath: string, stats: Stats) => void,
-    fileCallback: (normalizedPath: string, stats: Stats) => void,
-    symlinkCallback: (normalizedPath: string, stats: Stats) => void,
-    endCallback: () => void,
-    // $FlowFixMe[unclear-type] Add types for callback
-    errorCallback: Function,
-    ignored?: Matcher,
-  ) {
-    walker(dir)
-      .filterDir(
-        (currentDir: string) => !ignored || !anymatch(ignored, currentDir),
-      )
-      .on('dir', FSEventsWatcher._normalizeProxy(dirCallback))
-      .on('file', FSEventsWatcher._normalizeProxy(fileCallback))
-      .on('symlink', FSEventsWatcher._normalizeProxy(symlinkCallback))
-      .on('error', errorCallback)
-      .on('end', endCallback);
-  }
-
   constructor(
     dir: string,
     opts: $ReadOnly<{
-      ignored?: Matcher,
+      ignored: ?RegExp,
       glob: string | $ReadOnlyArray<string>,
       dot: boolean,
       ...
@@ -128,10 +95,10 @@ export default class FSEventsWatcher extends EventEmitter {
 
     this._tracked = new Set();
     const trackPath = (filePath: string) => {
-      this._tracked.add(filePath);
+      this._tracked.add(path.normalize(filePath));
     };
     this.watcherInitialReaddirPromise = new Promise(resolve => {
-      FSEventsWatcher._recReaddir(
+      recReaddir(
         this.root,
         trackPath,
         trackPath,
diff --git a/packages/metro-file-map/src/watchers/NodeWatcher.js b/packages/metro-file-map/src/watchers/NodeWatcher.js
index 4304f2cc8..183d99b1d 100644
--- a/packages/metro-file-map/src/watchers/NodeWatcher.js
+++ b/packages/metro-file-map/src/watchers/NodeWatcher.js
@@ -48,7 +48,7 @@ module.exports = class NodeWatcher extends EventEmitter {
   doIgnore: string => boolean;
   dot: boolean;
   globs: $ReadOnlyArray<string>;
-  ignored: ?(boolean | RegExp);
+  ignored: ?RegExp;
   root: string;
   watched: {[key: string]: FSWatcher, __proto__: null};
   watchmanDeferStates: $ReadOnlyArray<string>;
diff --git a/packages/metro-file-map/src/watchers/__tests__/WatchmanWatcher-test.js b/packages/metro-file-map/src/watchers/__tests__/WatchmanWatcher-test.js
index f4cccde53..876340d90 100644
--- a/packages/metro-file-map/src/watchers/__tests__/WatchmanWatcher-test.js
+++ b/packages/metro-file-map/src/watchers/__tests__/WatchmanWatcher-test.js
@@ -36,7 +36,7 @@ describe('WatchmanWatcher', () => {
   test('initializes with watch-project, clock, subscribe', () => {
     const watchmanWatcher = new WatchmanWatcher('/project/subdir/js', {
       dot: true,
-      ignored: false,
+      ignored: null,
       glob: ['**/*.js'],
       watchmanDeferStates: ['busy'],
     });
@@ -86,7 +86,7 @@ describe('WatchmanWatcher', () => {
     beforeEach(() => {
       watchmanWatcher = new WatchmanWatcher('/project/subdir/js', {
         dot: true,
-        ignored: false,
+        ignored: null,
         glob: ['**/*.js'],
         watchmanDeferStates: ['busy'],
       });
diff --git a/packages/metro-file-map/src/watchers/common.js b/packages/metro-file-map/src/watchers/common.js
index 2dbdb6d99..099ba1626 100644
--- a/packages/metro-file-map/src/watchers/common.js
+++ b/packages/metro-file-map/src/watchers/common.js
@@ -39,7 +39,7 @@ export const ALL_EVENT = 'all';
 export type WatcherOptions = $ReadOnly<{
   glob: $ReadOnlyArray<string>,
   dot: boolean,
-  ignored: boolean | RegExp,
+  ignored: ?RegExp,
   watchmanDeferStates: $ReadOnlyArray<string>,
   watchman?: mixed,
   watchmanPath?: string,
@@ -49,7 +49,7 @@ interface Watcher {
   doIgnore: string => boolean;
   dot: boolean;
   globs: $ReadOnlyArray<string>;
-  ignored?: ?(boolean | RegExp);
+  ignored?: ?RegExp;
   watchmanDeferStates: $ReadOnlyArray<string>;
   watchmanPath?: ?string;
 }
@@ -68,16 +68,14 @@ export const assignOptions = function (
 ): WatcherOptions {
   watcher.globs = opts.glob ?? [];
   watcher.dot = opts.dot ?? false;
-  watcher.ignored = opts.ignored ?? false;
+  watcher.ignored = opts.ignored ?? null;
   watcher.watchmanDeferStates = opts.watchmanDeferStates;
 
   if (!Array.isArray(watcher.globs)) {
     watcher.globs = [watcher.globs];
   }
   watcher.doIgnore =
-    opts.ignored != null && opts.ignored !== false
-      ? anymatch(opts.ignored)
-      : () => false;
+    opts.ignored != null ? anymatch(opts.ignored) : () => false;
 
   if (opts.watchman == true && opts.watchmanPath != null) {
     watcher.watchmanPath = opts.watchmanPath;
@@ -117,7 +115,7 @@ export function recReaddir(
   symlinkCallback: (string, Stats) => void,
   endCallback: () => void,
   errorCallback: Error => void,
-  ignored: ?(boolean | RegExp),
+  ignored: ?RegExp,
 ) {
   walker(dir)
     .filterDir(currentDir => !anymatch(ignored, currentDir))