diff --git a/lib/internal/test_runner/reporter/spec.js b/lib/internal/test_runner/reporter/spec.js
index 2410544d9736fe..0df89a90efa554 100644
--- a/lib/internal/test_runner/reporter/spec.js
+++ b/lib/internal/test_runner/reporter/spec.js
@@ -119,7 +119,7 @@ class SpecReporter extends Transform {
         break;
       case 'test:stderr':
       case 'test:stdout':
-        return `${data.message}\n`;
+        return data.message;
       case 'test:diagnostic':
         return `${colors[type]}${this.#indent(data.nesting)}${symbols[type]}${data.message}${white}\n`;
       case 'test:coverage':
diff --git a/lib/internal/test_runner/reporter/tap.js b/lib/internal/test_runner/reporter/tap.js
index 80289ef225788f..4aec4ba072d954 100644
--- a/lib/internal/test_runner/reporter/tap.js
+++ b/lib/internal/test_runner/reporter/tap.js
@@ -5,10 +5,10 @@ const {
   ArrayPrototypePush,
   ObjectEntries,
   RegExpPrototypeSymbolReplace,
+  RegExpPrototypeSymbolSplit,
   SafeMap,
   SafeSet,
   StringPrototypeReplaceAll,
-  StringPrototypeSplit,
   StringPrototypeRepeat,
 } = primordials;
 const { inspectWithNoCustomRetry } = require('internal/errors');
@@ -46,8 +46,14 @@ async function * tapReporter(source) {
         yield `${indent(data.nesting)}# Subtest: ${tapEscape(data.name)}\n`;
         break;
       case 'test:stderr':
-      case 'test:stdout':
-      case 'test:diagnostic':
+      case 'test:stdout': {
+        const lines = RegExpPrototypeSymbolSplit(kLineBreakRegExp, data.message);
+        for (let i = 0; i < lines.length; i++) {
+          if (lines[i].length === 0) continue;
+          yield `# ${tapEscape(lines[i])}\n`;
+        }
+        break;
+      } case 'test:diagnostic':
         yield `${indent(data.nesting)}# ${tapEscape(data.message)}\n`;
         break;
       case 'test:coverage':
@@ -124,7 +130,7 @@ function jsToYaml(indent, name, value, seen) {
       return `${prefix}${inspectWithNoCustomRetry(value, inspectOptions)}\n`;
     }
 
-    const lines = StringPrototypeSplit(value, kLineBreakRegExp);
+    const lines = RegExpPrototypeSymbolSplit(kLineBreakRegExp, value);
 
     if (lines.length === 1) {
       return `${prefix}${inspectWithNoCustomRetry(value, inspectOptions)}\n`;
@@ -224,7 +230,7 @@ function jsToYaml(indent, name, value, seen) {
       const frames = [];
 
       ArrayPrototypeForEach(
-        StringPrototypeSplit(errStack, kLineBreakRegExp),
+        RegExpPrototypeSymbolSplit(kLineBreakRegExp, errStack),
         (frame) => {
           const processed = RegExpPrototypeSymbolReplace(
             kFrameStartRegExp,
diff --git a/lib/internal/test_runner/runner.js b/lib/internal/test_runner/runner.js
index fcaf4ded1e42a8..6b5ed103c888bb 100644
--- a/lib/internal/test_runner/runner.js
+++ b/lib/internal/test_runner/runner.js
@@ -11,14 +11,12 @@ const {
   ArrayPrototypeSlice,
   ArrayPrototypeSome,
   ArrayPrototypeSort,
-  hardenRegExp,
   ObjectAssign,
   PromisePrototypeThen,
   SafePromiseAll,
   SafePromiseAllReturnVoid,
   SafePromiseAllSettledReturnVoid,
   PromiseResolve,
-  RegExpPrototypeSymbolSplit,
   SafeMap,
   SafeSet,
   StringPrototypeIndexOf,
@@ -75,7 +73,6 @@ const {
 const kFilterArgs = ['--test', '--experimental-test-coverage', '--watch'];
 const kFilterArgValues = ['--test-reporter', '--test-reporter-destination'];
 const kDiagnosticsFilterArgs = ['tests', 'suites', 'pass', 'fail', 'cancelled', 'skipped', 'todo', 'duration_ms'];
-const kSplitLine = hardenRegExp(/\r?\n/);
 
 const kCanceledTests = new SafeSet()
   .add(kCancelledByParent).add(kAborted).add(kTestTimeoutFailure);
@@ -301,15 +298,11 @@ class FileTest extends Test {
     }
 
     if (TypedArrayPrototypeGetLength(nonSerialized) > 0) {
-      const messages = RegExpPrototypeSymbolSplit(kSplitLine, nonSerialized.toString('utf-8'));
-      for (let i = 0; i < messages.length; i++) {
-        const message = messages[i];
-        this.addToReport({
-          __proto__: null,
-          type: 'test:stdout',
-          data: { __proto__: null, file: this.name, message },
-        });
-      }
+      this.addToReport({
+        __proto__: null,
+        type: 'test:stdout',
+        data: { __proto__: null, file: this.name, message: nonSerialized.toString('utf-8') },
+      });
     }
 
     while (bufferHead?.length >= kSerializedSizeHeader) {
@@ -383,7 +376,7 @@ function runTestFile(path, root, inspectPort, filesWatcher, testNamePatterns) {
       subtest.addToReport({
         __proto__: null,
         type: 'test:stderr',
-        data: { __proto__: null, file: path, message: line },
+        data: { __proto__: null, file: path, message: line + '\n' },
       });
     });