diff --git a/ChangeLog-8.5.md b/ChangeLog-8.5.md
index a65e6a61928..754affa9620 100644
--- a/ChangeLog-8.5.md
+++ b/ChangeLog-8.5.md
@@ -2,6 +2,12 @@
 
 All notable changes of the PHPUnit 8.5 release series are documented in this file using the [Keep a CHANGELOG](https://keepachangelog.com/) principles.
 
+## [8.5.34] - 2023-MM-DD
+
+### Changed
+
+* The child processes used for process isolation now use temporary files to communicate their result to the parent process
+
 ## [8.5.33] - 2023-02-27
 
 ### Fixed
@@ -268,6 +274,7 @@ All notable changes of the PHPUnit 8.5 release series are documented in this fil
 * [#3967](https://github.com/sebastianbergmann/phpunit/issues/3967): Cannot double interface that extends interface that extends `\Throwable`
 * [#3968](https://github.com/sebastianbergmann/phpunit/pull/3968): Test class run in a separate PHP process are passing when `exit` called inside
 
+[8.5.34]: https://github.com/sebastianbergmann/phpunit/compare/8.5.33...8.5
 [8.5.33]: https://github.com/sebastianbergmann/phpunit/compare/8.5.32...8.5.33
 [8.5.32]: https://github.com/sebastianbergmann/phpunit/compare/8.5.31...8.5.32
 [8.5.31]: https://github.com/sebastianbergmann/phpunit/compare/8.5.30...8.5.31
diff --git a/src/Framework/TestCase.php b/src/Framework/TestCase.php
index 0973056679e..889d8db40fb 100644
--- a/src/Framework/TestCase.php
+++ b/src/Framework/TestCase.php
@@ -59,6 +59,8 @@
 use function strlen;
 use function strpos;
 use function substr;
+use function sys_get_temp_dir;
+use function tempnam;
 use function trim;
 use function var_export;
 use DeepCopy\DeepCopy;
@@ -801,6 +803,7 @@ public function run(TestResult $result = null): TestResult
             $codeCoverageFilter = "'." . $codeCoverageFilter . ".'";
 
             $configurationFilePath = $GLOBALS['__PHPUNIT_CONFIGURATION_FILE'] ?? '';
+            $processResultFile     = tempnam(sys_get_temp_dir(), 'phpunit_');
 
             $var = [
                 'composerAutoload'                           => $composerAutoload,
@@ -824,6 +827,7 @@ public function run(TestResult $result = null): TestResult
                 'codeCoverageFilter'                         => $codeCoverageFilter,
                 'configurationFilePath'                      => $configurationFilePath,
                 'name'                                       => $this->getName(false),
+                'processResultFile'                          => $processResultFile,
             ];
 
             if (!$runEntireClass) {
@@ -833,7 +837,7 @@ public function run(TestResult $result = null): TestResult
             $template->setVar($var);
 
             $php = AbstractPhpProcess::factory();
-            $php->runTestJob($template->render(), $this, $result);
+            $php->runTestJob($template->render(), $this, $result, $processResultFile);
         } else {
             $result->run($this);
         }
diff --git a/src/Util/PHP/AbstractPhpProcess.php b/src/Util/PHP/AbstractPhpProcess.php
index 8706ae1a118..fc6bc6f14d2 100644
--- a/src/Util/PHP/AbstractPhpProcess.php
+++ b/src/Util/PHP/AbstractPhpProcess.php
@@ -15,6 +15,8 @@
 use function array_merge;
 use function assert;
 use function escapeshellarg;
+use function file_exists;
+use function file_get_contents;
 use function ini_get_all;
 use function restore_error_handler;
 use function set_error_handler;
@@ -24,6 +26,7 @@
 use function strrpos;
 use function substr;
 use function trim;
+use function unlink;
 use function unserialize;
 use __PHP_Incomplete_Class;
 use ErrorException;
@@ -174,16 +177,23 @@ public function getTimeout(): int
      *
      * @throws \SebastianBergmann\RecursionContext\InvalidArgumentException
      */
-    public function runTestJob(string $job, Test $test, TestResult $result): void
+    public function runTestJob(string $job, Test $test, TestResult $result, string $processResultFile): void
     {
         $result->startTest($test);
 
-        $_result = $this->runJob($job);
+        $processResult = '';
+        $_result       = $this->runJob($job);
+
+        if (file_exists($processResultFile)) {
+            $processResult = file_get_contents($processResultFile);
+
+            @unlink($processResultFile);
+        }
 
         $this->processChildResult(
             $test,
             $result,
-            $_result['stdout'],
+            $processResult,
             $_result['stderr']
         );
     }
diff --git a/src/Util/PHP/Template/TestCaseClass.tpl b/src/Util/PHP/Template/TestCaseClass.tpl
index bfcaed7fdcf..2ec3b9c33cc 100644
--- a/src/Util/PHP/Template/TestCaseClass.tpl
+++ b/src/Util/PHP/Template/TestCaseClass.tpl
@@ -70,13 +70,16 @@ function __phpunit_run_isolated_test()
         }
     }
 
-    print serialize(
-      [
-        'testResult'    => $test->getResult(),
-        'numAssertions' => $test->getNumAssertions(),
-        'result'        => $result,
-        'output'        => $output
-      ]
+    file_put_contents(
+        '{processResultFile}',
+        serialize(
+            [
+                'testResult'    => $test->getResult(),
+                'numAssertions' => $test->getNumAssertions(),
+                'result'        => $result,
+                'output'        => $output
+            ]
+        )
     );
 }
 
diff --git a/src/Util/PHP/Template/TestCaseMethod.tpl b/src/Util/PHP/Template/TestCaseMethod.tpl
index 94545ff8705..b0a692d941e 100644
--- a/src/Util/PHP/Template/TestCaseMethod.tpl
+++ b/src/Util/PHP/Template/TestCaseMethod.tpl
@@ -73,13 +73,16 @@ function __phpunit_run_isolated_test()
         }
     }
 
-    print serialize(
-      [
-        'testResult'    => $test->getResult(),
-        'numAssertions' => $test->getNumAssertions(),
-        'result'        => $result,
-        'output'        => $output
-      ]
+    file_put_contents(
+        '{processResultFile}',
+        serialize(
+            [
+                'testResult'    => $test->getResult(),
+                'numAssertions' => $test->getNumAssertions(),
+                'result'        => $result,
+                'output'        => $output
+            ]
+        )
     );
 }