diff --git a/src/Plugin.php b/src/Plugin.php
index fc1e830..611286b 100644
--- a/src/Plugin.php
+++ b/src/Plugin.php
@@ -18,7 +18,7 @@
 
 class Plugin implements PluginInterface, EventSubscriberInterface
 {
-    private ?Composer $composer = null;
+    private Composer $composer;
 
     /**
      * Array of installers to run following a dump-autoload operation.
@@ -27,7 +27,7 @@ class Plugin implements PluginInterface, EventSubscriberInterface
      */
     private array $installers = [];
 
-    private ?IOInterface $io = null;
+    private IOInterface $io ;
 
     /**
      * Provide composer event listeners.
diff --git a/test/AssetInstallerTest.php b/test/AssetInstallerTest.php
index d777b22..775eb28 100644
--- a/test/AssetInstallerTest.php
+++ b/test/AssetInstallerTest.php
@@ -46,10 +46,10 @@ class AssetInstallerTest extends TestCase
     ];
 
     /** @var PackageInterface|ObjectProphecy */
-    private ?ObjectProphecy $package = null;
+    private $package;
 
     /** @var IOInterface|ObjectProphecy */
-    private ?ObjectProphecy $io = null;
+    private $io;
 
     private vfsStreamDirectory $filesystem;
 
diff --git a/test/AssetUninstallerTest.php b/test/AssetUninstallerTest.php
index 5c2dd87..3a82497 100644
--- a/test/AssetUninstallerTest.php
+++ b/test/AssetUninstallerTest.php
@@ -86,10 +86,10 @@ class AssetUninstallerTest extends TestCase
     private vfsStreamDirectory $filesystem;
 
     /** @var PackageInterface|ObjectProphecy */
-    private ?ObjectProphecy $package = null;
+    private $package;
 
     /** @var IOInterface|ObjectProphecy */
-    private ?ObjectProphecy $io = null;
+    private $io;
 
     public function setUp(): void
     {
diff --git a/test/PluginTest.php b/test/PluginTest.php
index 920e7e4..83c2fe4 100644
--- a/test/PluginTest.php
+++ b/test/PluginTest.php
@@ -27,10 +27,10 @@ class PluginTest extends TestCase
     private vfsStreamDirectory $filesystem;
 
     /** @var Composer|ObjectProphecy */
-    private ObjectProphecy $composer;
+    private $composer;
 
     /** @var IOInterface|ObjectProphecy */
-    private ObjectProphecy $io;
+    private $io;
 
     public function setUp(): void
     {