diff --git a/src/Composer/InstalledPackageResolver.php b/src/Composer/InstalledPackageResolver.php
index c2046cfed6f..3593c9e5d4c 100644
--- a/src/Composer/InstalledPackageResolver.php
+++ b/src/Composer/InstalledPackageResolver.php
@@ -21,15 +21,14 @@ final class InstalledPackageResolver
      */
     private ?array $resolvedInstalledPackages = null;
 
-    public function __construct(
-        private readonly ?string $projectDirectory = null
-    ) {
+    private readonly string $projectDirectory;
+
+    public function __construct(?string $projectDirectory = null)
+    {
         // fallback to root project directory
-        if ($projectDirectory === null) {
-            $projectDirectory = getcwd();
-        }
+        $this->projectDirectory = $projectDirectory ?? (string) getcwd();
 
-        Assert::directory($projectDirectory);
+        Assert::directory($this->projectDirectory);
     }
 
     /**
diff --git a/tests/Composer/InstalledPackageResolverTest.php b/tests/Composer/InstalledPackageResolverTest.php
index 8b26d761324..81396d6edf3 100644
--- a/tests/Composer/InstalledPackageResolverTest.php
+++ b/tests/Composer/InstalledPackageResolverTest.php
@@ -18,4 +18,13 @@ public function test(): void
         $this->assertContainsOnlyInstancesOf(InstalledPackage::class, $installedPackages);
         $this->assertGreaterThan(77, count($installedPackages));
     }
+
+    public function testFallbackToCurrentWorkingDirectory(): void
+    {
+        $installedPackageResolver = new InstalledPackageResolver();
+        $installedPackages = $installedPackageResolver->resolve();
+
+        $this->assertContainsOnlyInstancesOf(InstalledPackage::class, $installedPackages);
+        $this->assertGreaterThan(77, count($installedPackages));
+    }
 }