diff --git a/packages/coverage-c8/src/provider.ts b/packages/coverage-c8/src/provider.ts
index f88630666ead..9797511a4435 100644
--- a/packages/coverage-c8/src/provider.ts
+++ b/packages/coverage-c8/src/provider.ts
@@ -86,6 +86,7 @@ export class C8CoverageProvider implements CoverageProvider {
           entry.map.mappings.length > 0
           && entry.map.sourcesContent
           && entry.map.sourcesContent.length > 0
+          && entry.map.sourcesContent[0]
           && entry.map.sourcesContent[0].length > 0
         )
       }) as SourceMapMeta[]
diff --git a/test/coverage-test/test/no-esbuild-transform.test.js b/test/coverage-test/test/no-esbuild-transform.test.js
new file mode 100644
index 000000000000..e6167c52b975
--- /dev/null
+++ b/test/coverage-test/test/no-esbuild-transform.test.js
@@ -0,0 +1,10 @@
+import { expect, test, vi } from 'vitest'
+import { add } from '../src/utils'
+
+vi.mock('../src/utils', async () => ({
+  add: vi.fn().mockReturnValue('mocked'),
+}))
+
+test('mocking in Javascript test should not break sourcemaps', () => {
+  expect(add(1, 2)).toBe('mocked')
+})
diff --git a/test/coverage-test/testing.mjs b/test/coverage-test/testing.mjs
index 8a0dc86f7a42..f419f1acbcab 100644
--- a/test/coverage-test/testing.mjs
+++ b/test/coverage-test/testing.mjs
@@ -8,7 +8,7 @@ const provider = getArgument('--provider')
 const configs = [
   // Run test cases. Generates coverage report.
   ['test/', {
-    include: ['test/*.test.ts'],
+    include: ['test/*.test.*'],
     exclude: ['coverage-report-tests/**/*'],
   }],