diff --git a/src/TestSuite.php b/src/TestSuite.php
index e3d9f772..b9c232b2 100644
--- a/src/TestSuite.php
+++ b/src/TestSuite.php
@@ -83,7 +83,7 @@ final class TestSuite
         $this->afterEach  = new AfterEachRepository();
         $this->afterAll   = new AfterAllRepository();
 
-        $this->rootPath = realpath($rootPath);
+        $this->rootPath = (string) realpath($rootPath);
     }
 
     /**