diff --git a/packages/jest-regex-util/src/__tests__/index.test.ts b/packages/jest-regex-util/src/__tests__/index.test.ts
index ecfa008fd662..d690106beeeb 100644
--- a/packages/jest-regex-util/src/__tests__/index.test.ts
+++ b/packages/jest-regex-util/src/__tests__/index.test.ts
@@ -11,7 +11,7 @@ describe('replacePathSepForRegex()', () => {
   describe('posix', () => {
     beforeAll(() => {
       jest.mock('path', () => ({
-        ...jest.createMockFromModule('path'),
+        ...jest.createMockFromModule<typeof import('path')>('path'),
         sep: '/',
       }));
       jest.isolateModules(() => {
@@ -21,14 +21,14 @@ describe('replacePathSepForRegex()', () => {
 
     it('should return the path', () => {
       const expected = {};
-      expect(replacePathSepForRegex(expected as any)).toBe(expected);
+      expect(replacePathSepForRegex(expected as string)).toBe(expected);
     });
   });
 
   describe('win32', () => {
     beforeAll(() => {
       jest.mock('path', () => ({
-        ...jest.createMockFromModule('path'),
+        ...jest.createMockFromModule<typeof import('path')>('path'),
         sep: '\\',
       }));
       jest.isolateModules(() => {
diff --git a/packages/jest-test-sequencer/src/__tests__/test_sequencer.test.ts b/packages/jest-test-sequencer/src/__tests__/test_sequencer.test.ts
index 52a48762e22c..88b5bb4b9c17 100644
--- a/packages/jest-test-sequencer/src/__tests__/test_sequencer.test.ts
+++ b/packages/jest-test-sequencer/src/__tests__/test_sequencer.test.ts
@@ -7,12 +7,12 @@
 
 import * as path from 'path';
 import * as mockedFs from 'graceful-fs';
-import type {Test, TestContext} from '@jest/test-result';
+import type {AggregatedResult, Test, TestContext} from '@jest/test-result';
 import {makeProjectConfig} from '@jest/test-utils';
 import TestSequencer from '../index';
 
 jest.mock('graceful-fs', () => ({
-  ...jest.createMockFromModule('fs'),
+  ...jest.createMockFromModule<typeof import('fs')>('fs'),
   existsSync: jest.fn(() => true),
   readFileSync: jest.fn(() => '{}'),
 }));
@@ -161,7 +161,9 @@ test('writes the cache based on results without existing cache', async () => {
       },
     ],
   });
-  const fileData = JSON.parse(fs.writeFileSync.mock.calls[0][1]);
+  const fileData = JSON.parse(
+    fs.writeFileSync.mock.calls[0][1],
+  ) as AggregatedResult;
   expect(fileData).toEqual({
     '/test-a.js': [SUCCESS, 1],
     '/test-c.js': [FAIL, 3],
@@ -219,7 +221,9 @@ test('writes the cache based on the results', async () => {
       },
     ],
   });
-  const fileData = JSON.parse(fs.writeFileSync.mock.calls[0][1]);
+  const fileData = JSON.parse(
+    fs.writeFileSync.mock.calls[0][1],
+  ) as AggregatedResult;
   expect(fileData).toEqual({
     '/test-a.js': [SUCCESS, 1],
     '/test-b.js': [FAIL, 1],
@@ -228,16 +232,20 @@ test('writes the cache based on the results', async () => {
 });
 
 test('works with multiple contexts', async () => {
-  fs.readFileSync.mockImplementationOnce(cacheName =>
-    cacheName.startsWith(`${path.sep}cache${path.sep}`)
+  fs.readFileSync.mockImplementationOnce(cacheName => {
+    if (typeof cacheName !== 'string') {
+      throw new Error('Must be called with a string');
+    }
+
+    return cacheName.startsWith(`${path.sep}cache${path.sep}`)
       ? JSON.stringify({
           '/test-a.js': [SUCCESS, 5],
           '/test-b.js': [FAIL, 1],
         })
       : JSON.stringify({
           '/test-c.js': [FAIL],
-        }),
-  );
+        });
+  });
 
   const testPaths = [
     {context, duration: null, path: '/test-a.js'},
@@ -270,12 +278,16 @@ test('works with multiple contexts', async () => {
       },
     ],
   });
-  const fileDataA = JSON.parse(fs.writeFileSync.mock.calls[0][1]);
+  const fileDataA = JSON.parse(
+    fs.writeFileSync.mock.calls[0][1],
+  ) as AggregatedResult;
   expect(fileDataA).toEqual({
     '/test-a.js': [SUCCESS, 1],
     '/test-b.js': [FAIL, 1],
   });
-  const fileDataB = JSON.parse(fs.writeFileSync.mock.calls[1][1]);
+  const fileDataB = JSON.parse(
+    fs.writeFileSync.mock.calls[1][1],
+  ) as AggregatedResult;
   expect(fileDataB).toEqual({
     '/test-c.js': [SUCCESS, 3],
   });
diff --git a/packages/jest-test-sequencer/src/index.ts b/packages/jest-test-sequencer/src/index.ts
index e21dc2028ef1..f55b5ea4c1f2 100644
--- a/packages/jest-test-sequencer/src/index.ts
+++ b/packages/jest-test-sequencer/src/index.ts
@@ -16,7 +16,7 @@ const FAIL = 0;
 const SUCCESS = 1;
 
 type Cache = {
-  [key: string]: [0 | 1, number];
+  [key: string]: [0 | 1, number] | undefined;
 };
 
 export type ShardOptions = {
@@ -57,7 +57,7 @@ export default class TestSequencer {
         try {
           this._cache.set(
             context,
-            JSON.parse(fs.readFileSync(cachePath, 'utf8')),
+            JSON.parse(fs.readFileSync(cachePath, 'utf8')) as Cache,
           );
         } catch {}
       }
@@ -156,21 +156,17 @@ export default class TestSequencer {
      */
     const stats: {[path: string]: number} = {};
     const fileSize = ({path, context: {hasteFS}}: Test) =>
-      stats[path] || (stats[path] = hasteFS.getSize(path) || 0);
-    const hasFailed = (cache: Cache, test: Test) =>
-      cache[test.path] && cache[test.path][0] === FAIL;
-    const time = (cache: Cache, test: Test) =>
-      cache[test.path] && cache[test.path][1];
+      stats[path] || (stats[path] = hasteFS.getSize(path) ?? 0);
 
-    tests.forEach(test => (test.duration = time(this._getCache(test), test)));
+    tests.forEach(test => {
+      test.duration = this.time(test);
+    });
     return tests.sort((testA, testB) => {
-      const cacheA = this._getCache(testA);
-      const cacheB = this._getCache(testB);
-      const failedA = hasFailed(cacheA, testA);
-      const failedB = hasFailed(cacheB, testB);
+      const failedA = this.hasFailed(testA);
+      const failedB = this.hasFailed(testB);
       const hasTimeA = testA.duration != null;
       if (failedA !== failedB) {
-        return failedA ? -1 : 1;
+        return failedA === true ? -1 : 1;
       } else if (hasTimeA != (testB.duration != null)) {
         // If only one of two tests has timing information, run it last
         return hasTimeA ? 1 : -1;
@@ -191,11 +187,12 @@ export default class TestSequencer {
   }
 
   cacheResults(tests: Array<Test>, results: AggregatedResult): void {
-    const map = Object.create(null);
+    const map = Object.create(null) as Record<string, Test | undefined>;
     tests.forEach(test => (map[test.path] = test));
     results.testResults.forEach(testResult => {
-      if (testResult && map[testResult.testFilePath] && !testResult.skipped) {
-        const cache = this._getCache(map[testResult.testFilePath]);
+      const test = map[testResult.testFilePath];
+      if (test != null && !testResult.skipped) {
+        const cache = this._getCache(test);
         const perf = testResult.perfStats;
         cache[testResult.testFilePath] = [
           testResult.numFailingTests ? FAIL : SUCCESS,
@@ -208,4 +205,14 @@ export default class TestSequencer {
       fs.writeFileSync(this._getCachePath(context), JSON.stringify(cache)),
     );
   }
+
+  private hasFailed(test: Test) {
+    const cache = this._getCache(test);
+    return cache[test.path]?.[0] === FAIL;
+  }
+
+  private time(test: Test) {
+    const cache = this._getCache(test);
+    return cache[test.path]?.[1];
+  }
 }
diff --git a/scripts/lintTs.mjs b/scripts/lintTs.mjs
index cbdfdf79fe6c..760bfb7abdd2 100644
--- a/scripts/lintTs.mjs
+++ b/scripts/lintTs.mjs
@@ -35,6 +35,7 @@ const packagesToTest = [
   'jest-schemas',
   'jest-source-map',
   'jest-test-result',
+  'jest-test-sequencer',
   'jest-transform',
   'jest-types',
   'test-globals',