diff --git a/src/Namers/PHPUnitNamer.php b/src/Namers/PHPUnitNamer.php
index b9904e2..3289e04 100644
--- a/src/Namers/PHPUnitNamer.php
+++ b/src/Namers/PHPUnitNamer.php
@@ -68,7 +68,7 @@ private static function endsWith($haystack, $needle)
         return substr($haystack, -$length) === $needle;
     }
 
-    public function __toString(): string {
+    public function __toString() {
         return "[PHPUnit,class,method,reflection,testDirectory]="
             ."[{$this->isPHPUnitTest},{$this->class},{$this->function},{$this->isReflection},{$this->testDirectory}]";
     }