diff --git a/src/FileEnumeratorIsh.js b/src/FileEnumeratorIsh.js
new file mode 100644
index 000000000..948f8a1b5
--- /dev/null
+++ b/src/FileEnumeratorIsh.js
@@ -0,0 +1,221 @@
+const fs = require("fs");
+const path = require("path");
+const escapeRegExp = require("escape-string-regexp");
+
+const dotfilesPattern = /(?:(?:^\.)|(?:[/\\]\.))[^/\\.].*/u;
+const NONE = 0;
+const IGNORED_SILENTLY = 1;
+
+/**
+ * @typedef {Object} FileEnumeratorOptions
+ * @property {CascadingConfigArrayFactory} [configArrayFactory] The factory for config arrays.
+ * @property {string} [cwd] The base directory to start lookup.
+ * @property {string[]} [extensions] The extensions to match files for directory patterns.
+ * @property {(directoryPath: string) => boolean} [isDirectoryIgnored] Returns whether a directory is ignored.
+ * @property {(filePath: string) => boolean} [isFileIgnored] Returns whether a file is ignored.
+ */
+
+/**
+ * @typedef {Object} FileAndIgnored
+ * @property {string} filePath The path to a target file.
+ * @property {boolean} ignored If `true` then this file should be ignored and warned because it was directly specified.
+ */
+
+/**
+ * @typedef {Object} FileEntry
+ * @property {string} filePath The path to a target file.
+ * @property {ConfigArray} config The config entries of that file.
+ * @property {NONE|IGNORED_SILENTLY} flag The flag.
+ * - `NONE` means the file is a target file.
+ * - `IGNORED_SILENTLY` means the file should be ignored silently.
+ */
+
+/**
+ * Get stats of a given path.
+ * @param {string} filePath The path to target file.
+ * @throws {Error} As may be thrown by `fs.statSync`.
+ * @returns {fs.Stats|null} The stats.
+ * @private
+ */
+function statSafeSync(filePath) {
+  try {
+    return fs.statSync(filePath);
+  } catch (error) {
+    /* c8 ignore next */
+    if (error.code !== "ENOENT") {
+      throw error;
+    }
+    return null;
+  }
+}
+
+/**
+ * Get filenames in a given path to a directory.
+ * @param {string} directoryPath The path to target directory.
+ * @throws {Error} As may be thrown by `fs.readdirSync`.
+ * @returns {import("fs").Dirent[]} The filenames.
+ * @private
+ */
+function readdirSafeSync(directoryPath) {
+  try {
+    return fs.readdirSync(directoryPath, { withFileTypes: true });
+  } catch (error) {
+    /* c8 ignore next */
+    if (error.code !== "ENOENT") {
+      throw error;
+    }
+    return [];
+  }
+}
+
+/**
+ * Create a `RegExp` object to detect extensions.
+ * @param {string[] | null} extensions The extensions to create.
+ * @returns {RegExp | null} The created `RegExp` object or null.
+ */
+function createExtensionRegExp(extensions) {
+  if (extensions) {
+    const normalizedExts = extensions.map((ext) =>
+      escapeRegExp(ext.startsWith(".") ? ext.slice(1) : ext)
+    );
+
+    return new RegExp(`.\\.(?:${normalizedExts.join("|")})$`, "u");
+  }
+  return null;
+}
+
+/**
+ * This class provides the functionality that enumerates every file which is
+ * matched by given glob patterns and that configuration.
+ */
+export class FileEnumeratorIsh {
+  /**
+   * Initialize this enumerator.
+   * @param {FileEnumeratorOptions} options The options.
+   */
+  constructor({
+    cwd = process.cwd(),
+    extensions = null,
+    isDirectoryIgnored,
+    isFileIgnored,
+  } = {}) {
+    this.cwd = cwd;
+    this.extensionRegExp = createExtensionRegExp(extensions);
+    this.isDirectoryIgnored = isDirectoryIgnored;
+    this.isFileIgnored = isFileIgnored;
+  }
+
+  /**
+   * Iterate files which are matched by given glob patterns.
+   * @param {string|string[]} patternOrPatterns The glob patterns to iterate files.
+   * @returns {IterableIterator<FileAndIgnored>} The found files.
+   */
+  *iterateFiles(patternOrPatterns) {
+    const patterns = Array.isArray(patternOrPatterns)
+      ? patternOrPatterns
+      : [patternOrPatterns];
+
+    // The set of paths to remove duplicate.
+    const set = new Set();
+
+    for (const pattern of patterns) {
+      // Skip empty string.
+      if (!pattern) {
+        continue;
+      }
+
+      // Iterate files of this pattern.
+      for (const { filePath, flag } of this._iterateFiles(pattern)) {
+        if (flag === IGNORED_SILENTLY) {
+          continue;
+        }
+
+        // Remove duplicate paths while yielding paths.
+        if (!set.has(filePath)) {
+          set.add(filePath);
+          yield {
+            filePath,
+            ignored: false,
+          };
+        }
+      }
+    }
+  }
+
+  /**
+   * Iterate files which are matched by a given glob pattern.
+   * @param {string} pattern The glob pattern to iterate files.
+   * @returns {IterableIterator<FileEntry>} The found files.
+   */
+  _iterateFiles(pattern) {
+    const { cwd } = this;
+    const absolutePath = path.resolve(cwd, pattern);
+    const isDot = dotfilesPattern.test(pattern);
+    const stat = statSafeSync(absolutePath);
+
+    if (!stat) {
+      return [];
+    }
+
+    if (stat.isDirectory()) {
+      return this._iterateFilesWithDirectory(absolutePath, isDot);
+    }
+
+    if (stat.isFile()) {
+      return this._iterateFilesWithFile(absolutePath);
+    }
+  }
+
+  /**
+   * Iterate files in a given path.
+   * @param {string} directoryPath The path to the target directory.
+   * @param {boolean} dotfiles If `true` then it doesn't skip dot files by default.
+   * @returns {IterableIterator<FileEntry>} The found files.
+   * @private
+   */
+  _iterateFilesWithDirectory(directoryPath, dotfiles) {
+    return this._iterateFilesRecursive(directoryPath, { dotfiles });
+  }
+
+  /**
+   * Iterate files in a given path.
+   * @param {string} directoryPath The path to the target directory.
+   * @param {Object} options The options to iterate files.
+   * @param {boolean} [options.dotfiles] If `true` then it doesn't skip dot files by default.
+   * @param {boolean} [options.recursive] If `true` then it dives into sub directories.
+   * @returns {IterableIterator<FileEntry>} The found files.
+   * @private
+   */
+  *_iterateFilesRecursive(directoryPath, options) {
+    // Enumerate the files of this directory.
+    for (const entry of readdirSafeSync(directoryPath)) {
+      const filePath = path.join(directoryPath, entry.name);
+      const fileInfo = entry.isSymbolicLink() ? statSafeSync(filePath) : entry;
+
+      if (!fileInfo) {
+        continue;
+      }
+
+      // Check if the file is matched.
+      if (fileInfo.isFile()) {
+        if (this.extensionRegExp.test(filePath)) {
+          const ignored = this.isFileIgnored(filePath, options.dotfiles);
+          const flag = ignored ? IGNORED_SILENTLY : NONE;
+
+          yield { filePath, flag };
+        }
+
+        // Dive into the sub directory.
+      } else if (fileInfo.isDirectory()) {
+        const ignored = this.isDirectoryIgnored(
+          filePath + path.sep,
+          options.dotfiles
+        );
+
+        if (!ignored) {
+          yield* this._iterateFilesRecursive(filePath, options);
+        }
+      }
+    }
+  }
+}
diff --git a/src/rules/no-unused-modules.js b/src/rules/no-unused-modules.js
index ec3425dac..d864f1427 100644
--- a/src/rules/no-unused-modules.js
+++ b/src/rules/no-unused-modules.js
@@ -15,53 +15,22 @@ import flatMap from 'array.prototype.flatmap';
 
 import Exports, { recursivePatternCapture } from '../ExportMap';
 import docsUrl from '../docsUrl';
+import { FileEnumeratorIsh } from '../FileEnumeratorIsh';
 
-let FileEnumerator;
-let listFilesToProcess;
-
-try {
-  ({ FileEnumerator } = require('eslint/use-at-your-own-risk'));
-} catch (e) {
-  try {
-    // has been moved to eslint/lib/cli-engine/file-enumerator in version 6
-    ({ FileEnumerator } = require('eslint/lib/cli-engine/file-enumerator'));
-  } catch (e) {
-    try {
-      // eslint/lib/util/glob-util has been moved to eslint/lib/util/glob-utils with version 5.3
-      const { listFilesToProcess: originalListFilesToProcess } = require('eslint/lib/util/glob-utils');
-
-      // Prevent passing invalid options (extensions array) to old versions of the function.
-      // https://github.com/eslint/eslint/blob/v5.16.0/lib/util/glob-utils.js#L178-L280
-      // https://github.com/eslint/eslint/blob/v5.2.0/lib/util/glob-util.js#L174-L269
-      listFilesToProcess = function (src, extensions) {
-        return originalListFilesToProcess(src, {
-          extensions,
-        });
-      };
-    } catch (e) {
-      const { listFilesToProcess: originalListFilesToProcess } = require('eslint/lib/util/glob-util');
-
-      listFilesToProcess = function (src, extensions) {
-        const patterns = src.concat(flatMap(src, (pattern) => extensions.map((extension) => (/\*\*|\*\./).test(pattern) ? pattern : `${pattern}/**/*${extension}`)));
-
-        return originalListFilesToProcess(patterns);
-      };
-    }
-  }
-}
+const listFilesToProcess = function (context, src) {
+  const extensions = Array.from(getFileExtensions(context.settings));
 
-if (FileEnumerator) {
-  listFilesToProcess = function (src, extensions) {
-    const e = new FileEnumerator({
-      extensions,
-    });
+  const e = new FileEnumeratorIsh({
+    cwd: context.cwd,
+    extensions,
+    ...context.session,
+  });
 
-    return Array.from(e.iterateFiles(src), ({ filePath, ignored }) => ({
-      ignored,
-      filename: filePath,
-    }));
-  };
-}
+  return Array.from(e.iterateFiles(src), ({ filePath, ignored }) => ({
+    ignored,
+    filename: filePath,
+  }));
+};
 
 const EXPORT_DEFAULT_DECLARATION = 'ExportDefaultDeclaration';
 const EXPORT_NAMED_DECLARATION = 'ExportNamedDeclaration';
@@ -171,12 +140,10 @@ const isNodeModule = (path) => (/\/(node_modules)\//).test(path);
  * return all files matching src pattern, which are not matching the ignoreExports pattern
  */
 const resolveFiles = (src, ignoreExports, context) => {
-  const extensions = Array.from(getFileExtensions(context.settings));
-
-  const srcFileList = listFilesToProcess(src, extensions);
+  const srcFileList = listFilesToProcess(context, src);
 
   // prepare list of ignored files
-  const ignoredFilesList = listFilesToProcess(ignoreExports, extensions);
+  const ignoredFilesList = listFilesToProcess(context, ignoreExports);
   ignoredFilesList.forEach(({ filename }) => ignoredFiles.add(filename));
 
   // prepare list of source files, don't consider files from node_modules