diff --git a/src/Composer/DependencyResolver/Pool.php b/src/Composer/DependencyResolver/Pool.php
index 348583513ebc..ceb8777ee429 100644
--- a/src/Composer/DependencyResolver/Pool.php
+++ b/src/Composer/DependencyResolver/Pool.php
@@ -79,6 +79,7 @@ public function packageById($id)
     /**
      * Returns how many packages have been loaded into the pool
      */
+    #[\ReturnTypeWillChange]
     public function count()
     {
         return \count($this->packages);
diff --git a/src/Composer/Repository/ArrayRepository.php b/src/Composer/Repository/ArrayRepository.php
index 90cf938f4210..07aa04db12bc 100644
--- a/src/Composer/Repository/ArrayRepository.php
+++ b/src/Composer/Repository/ArrayRepository.php
@@ -283,6 +283,7 @@ public function getPackages()
      *
      * @return int Number of packages
      */
+    #[\ReturnTypeWillChange]
     public function count()
     {
         if (null === $this->packages) {
diff --git a/tests/Composer/Test/Platform/HhvmDetectorTest.php b/tests/Composer/Test/Platform/HhvmDetectorTest.php
index 51926156cd8c..2c435ed73b99 100644
--- a/tests/Composer/Test/Platform/HhvmDetectorTest.php
+++ b/tests/Composer/Test/Platform/HhvmDetectorTest.php
@@ -68,7 +68,11 @@ public function testHHVMVersionWhenExecutingInPHP()
         self::assertSame(self::getVersionParser()->normalize($version), self::getVersionParser()->normalize($detectedVersion));
     }
 
-    /** @runInSeparateProcess */
+    /**
+     * @runInSeparateProcess
+     * @preserveGlobalState disabled
+     * @requires PHP < 8.0.99
+     */
     public function testHHVMVersionWhenRunningInHHVMWithMockedConstant()
     {
         if (!defined('HHVM_VERSION_ID')) {
diff --git a/tests/Composer/Test/Util/ProcessExecutorTest.php b/tests/Composer/Test/Util/ProcessExecutorTest.php
index 988682c01fb0..ca2a8112b53b 100644
--- a/tests/Composer/Test/Util/ProcessExecutorTest.php
+++ b/tests/Composer/Test/Util/ProcessExecutorTest.php
@@ -111,7 +111,7 @@ public function testConsoleIODoesNotFormatSymfonyConsoleStyle()
         $output = new BufferedOutput(OutputInterface::VERBOSITY_NORMAL, true);
         $process = new ProcessExecutor(new ConsoleIO(new ArrayInput(array()), $output, new HelperSet(array())));
 
-        $process->execute('php -r "echo \'<error>foo</error>\'.PHP_EOL;"');
+        $process->execute('php -ddisplay_errors=0 -derror_reporting=0 -r "echo \'<error>foo</error>\'.PHP_EOL;"');
         $this->assertSame('<error>foo</error>'.PHP_EOL, $output->fetch());
     }