diff --git a/src/CodeIQ/Greeter/Greeter.php b/src/CodeIQ/Greeter/Greeter.php
index b13d32c..e623873 100644
--- a/src/CodeIQ/Greeter/Greeter.php
+++ b/src/CodeIQ/Greeter/Greeter.php
@@ -26,10 +26,19 @@ function __construct(Clock $clock)
     public function greet()
     {
         $currentTime = $this->clock->getCurrentTime();
-        if ($currentTime >= new \DateTimeImmutable('05:00:00') &&
-            $currentTime < new \DateTimeImmutable('12:00:00')
+        if ($this->timeIsMorning($currentTime)
         ) {
             return 'おはようございます';
         }
     }
+
+    /**
+     * @param $currentTime
+     * @return bool
+     */
+    private function timeIsMorning($currentTime)
+    {
+        return $currentTime >= new \DateTimeImmutable('05:00:00') &&
+        $currentTime < new \DateTimeImmutable('12:00:00');
+    }
 }