diff --git a/tests/phpunit/src/BltProjectTestBase.php b/tests/phpunit/src/BltProjectTestBase.php
index b2ae3e6b9..373a41f43 100644
--- a/tests/phpunit/src/BltProjectTestBase.php
+++ b/tests/phpunit/src/BltProjectTestBase.php
@@ -54,7 +54,7 @@ public function __construct($name = NULL, array $data = [], $dataName = '') {
       throw new \Exception("Could not find project.yml!");
     }
     if (file_exists("{$this->projectDirectory}/blt/project.local.yml")) {
-      $this->config = array_replace_recursive($this->config, Yaml::parse(file_get_contents("{$this->projectDirectory}/blt/project.local.yml")));
+      $this->config = array_replace_recursive($this->config, (array) Yaml::parse(file_get_contents("{$this->projectDirectory}/blt/project.local.yml")));
     }
   }