diff --git a/composer.json b/composer.json
index 0e51ffd98..bc956b021 100644
--- a/composer.json
+++ b/composer.json
@@ -39,7 +39,8 @@
         "phpbench/phpbench":            "^0.16.10",
         "infection/infection":          "^0.15.0",
         "symfony/console":              "^4.4.2",
-        "vimeo/psalm":                  "3.7.0"
+        "vimeo/psalm":                  "3.7.0",
+        "mikey179/vfsstream": "^1.6.8"
     },
     "suggest": {
         "ocramius/generated-hydrator": "To have very fast object to array to object conversion for ghost objects",
diff --git a/src/ProxyManager/FileLocator/FileLocator.php b/src/ProxyManager/FileLocator/FileLocator.php
index e9c2cbf23..abff30bb8 100644
--- a/src/ProxyManager/FileLocator/FileLocator.php
+++ b/src/ProxyManager/FileLocator/FileLocator.php
@@ -6,6 +6,7 @@
 
 use ProxyManager\Exception\InvalidProxyDirectoryException;
 use const DIRECTORY_SEPARATOR;
+use function is_dir;
 use function realpath;
 use function str_replace;
 
@@ -24,10 +25,12 @@ public function __construct(string $proxiesDirectory)
         $absolutePath = realpath($proxiesDirectory);
 
         if ($absolutePath === false) {
-            throw InvalidProxyDirectoryException::proxyDirectoryNotFound($proxiesDirectory);
+            if (! is_dir($proxiesDirectory)) {
+                throw InvalidProxyDirectoryException::proxyDirectoryNotFound($proxiesDirectory);
+            }
         }
 
-        $this->proxiesDirectory = $absolutePath;
+        $this->proxiesDirectory = $absolutePath ?: $proxiesDirectory;
     }
 
     /**
diff --git a/tests/ProxyManagerTest/FileLocator/FileLocatorTest.php b/tests/ProxyManagerTest/FileLocator/FileLocatorTest.php
index 3efcd412d..58447bc6c 100644
--- a/tests/ProxyManagerTest/FileLocator/FileLocatorTest.php
+++ b/tests/ProxyManagerTest/FileLocator/FileLocatorTest.php
@@ -4,6 +4,7 @@
 
 namespace ProxyManagerTest\FileLocator;
 
+use org\bovigo\vfs\vfsStream;
 use PHPUnit\Framework\TestCase;
 use ProxyManager\Exception\InvalidProxyDirectoryException;
 use ProxyManager\FileLocator\FileLocator;
@@ -36,4 +37,16 @@ public function testRejectsNonExistingDirectory() : void
         $this->expectException(InvalidProxyDirectoryException::class);
         new FileLocator(__DIR__ . '/non-existing');
     }
+
+    /**
+     * @covers \ProxyManager\FileLocator\FileLocator::__construct
+     */
+    public function testStreamWrappersSupported() : void
+    {
+        $vfs     = vfsStream::setup('root', null, ['dir' => []]);
+        $path    = $vfs->url() . '/dir';
+        $locator = new FileLocator($path);
+        self::assertSame($path . DIRECTORY_SEPARATOR . 'FooBarBaz.php', $locator->getProxyFileName('Foo\\Bar\\Baz'));
+        self::assertSame($path . DIRECTORY_SEPARATOR . 'Foo_Bar_Baz.php', $locator->getProxyFileName('Foo_Bar_Baz'));
+    }
 }