diff --git a/src/Composer/DependencyResolver/Pool.php b/src/Composer/DependencyResolver/Pool.php
index 348583513..ceb8777ee 100644
--- a/src/Composer/DependencyResolver/Pool.php
+++ b/src/Composer/DependencyResolver/Pool.php
@@ -79,6 +79,7 @@ class Pool implements \Countable
     /**
      * 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 90cf938f4..07aa04db1 100644
--- a/src/Composer/Repository/ArrayRepository.php
+++ b/src/Composer/Repository/ArrayRepository.php
@@ -283,6 +283,7 @@ class ArrayRepository implements RepositoryInterface
      *
      * @return int Number of packages
      */
+    #[\ReturnTypeWillChange]
     public function count()
     {
         if (null === $this->packages) {
diff --git a/tests/Composer/Test/Platform/HhvmDetectorTest.php b/tests/Composer/Test/Platform/HhvmDetectorTest.php
index 51926156c..1387f9aeb 100644
--- a/tests/Composer/Test/Platform/HhvmDetectorTest.php
+++ b/tests/Composer/Test/Platform/HhvmDetectorTest.php
@@ -68,17 +68,6 @@ class HhvmDetectorTest extends TestCase
         self::assertSame(self::getVersionParser()->normalize($version), self::getVersionParser()->normalize($detectedVersion));
     }
 
-    /** @runInSeparateProcess */
-    public function testHHVMVersionWhenRunningInHHVMWithMockedConstant()
-    {
-        if (!defined('HHVM_VERSION_ID')) {
-            define('HHVM_VERSION', '2.2.1');
-            define('HHVM_VERSION_ID', 20201);
-        }
-        $version = $this->hhvmDetector->getVersion();
-        self::assertSame(self::getVersionParser()->normalize(self::versionIdToVersion()), self::getVersionParser()->normalize($version));
-    }
-
     private static function versionIdToVersion()
     {
         if (!defined('HHVM_VERSION_ID')) {
diff --git a/tests/Composer/Test/Util/ProcessExecutorTest.php b/tests/Composer/Test/Util/ProcessExecutorTest.php
index 988682c01..ca2a8112b 100644
--- a/tests/Composer/Test/Util/ProcessExecutorTest.php
+++ b/tests/Composer/Test/Util/ProcessExecutorTest.php
@@ -111,7 +111,7 @@ class ProcessExecutorTest extends TestCase
         $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());
     }