diff --git a/bin/phpstan b/bin/phpstan
index a5837566a5..41969b6d7f 100755
--- a/bin/phpstan
+++ b/bin/phpstan
@@ -14,10 +14,8 @@ use PHPStan\Command\DumpDependenciesCommand;
 	$autoloaderInWorkingDirectory = getcwd() . '/vendor/autoload.php';
 	$composerAutoloaderProjectPaths = [];
 	if (is_file($autoloaderInWorkingDirectory)) {
-		$composerJsonPath = dirname($autoloaderInWorkingDirectory, 2);
-		if (is_file($composerJsonPath . '/composer.json')) {
-			$composerAutoloaderProjectPaths[] = $composerJsonPath;
-		}
+		$composerAutoloaderProjectPaths[] = dirname($autoloaderInWorkingDirectory, 2);
+
 		require_once $autoloaderInWorkingDirectory;
 	}
 
@@ -25,29 +23,23 @@ use PHPStan\Command\DumpDependenciesCommand;
 		$path = dirname(__DIR__) . $file;
 		if (!extension_loaded('phar')) {
 			if (is_file($path)) {
-				$composerJsonPath = dirname($path, 2);
-				if (is_file($composerJsonPath . '/composer.json')) {
-					$composerAutoloaderProjectPaths[] = $composerJsonPath;
-				}
+				$composerAutoloaderProjectPaths[] = dirname($path, 2);
+
 				require_once $path;
 			}
 		} else {
 			$pharPath = \Phar::running(false);
 			if ($pharPath === '') {
 				if (is_file($path)) {
-					$composerJsonPath = dirname($path, 2);
-					if (is_file($composerJsonPath . '/composer.json')) {
-						$composerAutoloaderProjectPaths[] = $composerJsonPath;
-					}
+					$composerAutoloaderProjectPaths[] = dirname($path, 2);
+
 					require_once $path;
 				}
 			} else {
 				$path = dirname($pharPath) . $file;
 				if (is_file($path)) {
-					$composerJsonPath = dirname($path, 2);
-					if (is_file($composerJsonPath . '/composer.json')) {
-						$composerAutoloaderProjectPaths[] = $composerJsonPath;
-					}
+					$composerAutoloaderProjectPaths[] = dirname($path, 2);
+
 					require_once $path;
 				}
 			}
diff --git a/src/Reflection/BetterReflection/BetterReflectionSourceLocatorFactory.php b/src/Reflection/BetterReflection/BetterReflectionSourceLocatorFactory.php
index 7d39f72467..e8887481f9 100644
--- a/src/Reflection/BetterReflection/BetterReflectionSourceLocatorFactory.php
+++ b/src/Reflection/BetterReflection/BetterReflectionSourceLocatorFactory.php
@@ -95,7 +95,11 @@ public function create(): SourceLocator
 		$locators = [];
 
 		foreach ($this->composerAutoloaderProjectPaths as $composerAutoloaderProjectPath) {
-			$locators[] = $this->composerJsonAndInstalledJsonSourceLocatorMaker->create($composerAutoloaderProjectPath);
+			$locator = $this->composerJsonAndInstalledJsonSourceLocatorMaker->create($composerAutoloaderProjectPath);
+			if ($locator === null) {
+				continue;
+			}
+			$locators[] =  $locator;
 		}
 
 		if ($this->enableScanningPaths) {
diff --git a/src/Reflection/BetterReflection/SourceLocator/ComposerJsonAndInstalledJsonSourceLocatorMaker.php b/src/Reflection/BetterReflection/SourceLocator/ComposerJsonAndInstalledJsonSourceLocatorMaker.php
index 1da1ad1f4c..3cb7a7410c 100644
--- a/src/Reflection/BetterReflection/SourceLocator/ComposerJsonAndInstalledJsonSourceLocatorMaker.php
+++ b/src/Reflection/BetterReflection/SourceLocator/ComposerJsonAndInstalledJsonSourceLocatorMaker.php
@@ -37,10 +37,16 @@ public function __construct(
 		$this->enableScanningPaths = $enableScanningPaths;
 	}
 
-	public function create(string $installationPath): SourceLocator
+	public function create(string $installationPath): ?SourceLocator
 	{
 		$composerJsonPath = $installationPath . '/composer.json';
+		if (!is_file($composerJsonPath)) {
+			return null;
+		}
 		$installedJsonPath = $installationPath . '/vendor/composer/installed.json';
+		if (!is_file($installedJsonPath)) {
+			return null;
+		}
 
 		$composerJsonContents = FileReader::read($composerJsonPath);
 		$composer = Json::decode($composerJsonContents, Json::FORCE_ARRAY);