diff --git a/tests/LINEBot/HTTPClient/CurlHTTPClientTest.php b/tests/LINEBot/HTTPClient/CurlHTTPClientTest.php
index 63b17fee..a1523558 100644
--- a/tests/LINEBot/HTTPClient/CurlHTTPClientTest.php
+++ b/tests/LINEBot/HTTPClient/CurlHTTPClientTest.php
@@ -52,10 +52,8 @@ public static function setUpBeforeClass()
             return;
         }
 
-        echo <<<"EOS"
-\n[WARN] req_mirror does not exist. Please try to execute `make install-devtool`
-[WARN] Skip CurlHTTPClientTest\n
-EOS;
+        echo PHP_EOL, '[WARN] req_mirror does not exist. Please try to execute `make install-devtool`', PHP_EOL;
+        echo '[WARN] Skip CurlHTTPClientTest', PHP_EOL;
     }
 
     public static function tearDownAfterClass()