diff --git a/lib/internal/test_runner/reporter/junit.js b/lib/internal/test_runner/reporter/junit.js
index ed25a4bd5fbd..5052f5444c0d 100644
--- a/lib/internal/test_runner/reporter/junit.js
+++ b/lib/internal/test_runner/reporter/junit.js
@@ -41,7 +41,7 @@ function treeToXML(tree) {
     tag, attrs, nesting, children, comment,
   } = tree;
   const indent = StringPrototypeRepeat('\t', nesting + 1);
-  if (comment) {
+  if (comment != null) {
     return `${indent}<!-- ${escapeComment(comment)} -->\n`;
   }
   const attrsString = ArrayPrototypeJoin(
diff --git a/test/fixtures/test-runner/output/junit_empty_diagnostic.js b/test/fixtures/test-runner/output/junit_empty_diagnostic.js
new file mode 100644
index 000000000000..491c2f230d98
--- /dev/null
+++ b/test/fixtures/test-runner/output/junit_empty_diagnostic.js
@@ -0,0 +1,8 @@
+// Flags: --test --test-reporter=junit
+'use strict';
+const test = require('node:test');
+
+test('failing', (t) => {
+  t.diagnostic('');
+  throw new Error('error');
+});
diff --git a/test/fixtures/test-runner/output/junit_empty_diagnostic.snapshot b/test/fixtures/test-runner/output/junit_empty_diagnostic.snapshot
new file mode 100644
index 000000000000..666c5c3523a7
--- /dev/null
+++ b/test/fixtures/test-runner/output/junit_empty_diagnostic.snapshot
@@ -0,0 +1,23 @@
+<?xml version="1.0" encoding="utf-8"?>
+<testsuites>
+	<testcase name="failing" time="*" classname="test" file="*" failure="error">
+		<failure type="testCodeFailure" message="error">
+[Error [ERR_TEST_FAILURE]: error] {
+  code: 'ERR_TEST_FAILURE',
+  failureType: 'testCodeFailure',
+  cause: Error: error
+      at TestContext.&lt;anonymous> (<project-root>/test/fixtures/test-runner/output/junit_empty_diagnostic.js:7:9)
+      at <node-internal-frames>
+}
+		</failure>
+	</testcase>
+	<!--  -->
+	<!-- tests 1 -->
+	<!-- suites 0 -->
+	<!-- pass 0 -->
+	<!-- fail 1 -->
+	<!-- cancelled 0 -->
+	<!-- skipped 0 -->
+	<!-- todo 0 -->
+	<!-- duration_ms * -->
+</testsuites>
diff --git a/test/test-runner/test-output-junit-empty-diagnostic.mjs b/test/test-runner/test-output-junit-empty-diagnostic.mjs
new file mode 100644
index 000000000000..5c1cf4a2b382
--- /dev/null
+++ b/test/test-runner/test-output-junit-empty-diagnostic.mjs
@@ -0,0 +1,11 @@
+// Test that the output of test-runner/output/junit_empty_diagnostic.js matches
+// test-runner/output/junit_empty_diagnostic.snapshot
+import '../common/index.mjs';
+import * as fixtures from '../common/fixtures.mjs';
+import { spawnAndAssert, junitTransform, ensureCwdIsProjectRoot } from '../common/assertSnapshot.js';
+
+ensureCwdIsProjectRoot();
+await spawnAndAssert(
+  fixtures.path('test-runner/output/junit_empty_diagnostic.js'),
+  junitTransform,
+);