diff --git a/.github/workflows/coding-standard-check.yml b/.github/workflows/coding-standard-check.yml
index a31d24a..708cfc3 100644
--- a/.github/workflows/coding-standard-check.yml
+++ b/.github/workflows/coding-standard-check.yml
@@ -29,7 +29,6 @@ jobs:
       fail-fast: false
       matrix:
         php-version:
-          - "7.1"
           - "7.2"
           - "7.3"
           - "7.4"
diff --git a/composer.json b/composer.json
index 9a0e94b..cb954e7 100644
--- a/composer.json
+++ b/composer.json
@@ -31,7 +31,7 @@
   "require-dev": {
     "phpunit/phpunit": "^5.7 || ^9.5",
     "friendsofphp/php-cs-fixer": "^2.19.3 || ^3.9.5",
-    "phpstan/phpstan": "1.4.*",
+    "phpstan/phpstan": "1.11.0",
     "vlucas/phpdotenv": "5.5.0"
   },
   "autoload": {
diff --git a/lib/omise/res/OmiseApiResource.php b/lib/omise/res/OmiseApiResource.php
index 0619990..5f49170 100644
--- a/lib/omise/res/OmiseApiResource.php
+++ b/lib/omise/res/OmiseApiResource.php
@@ -37,7 +37,7 @@ class OmiseApiResource extends OmiseObject
      */
     protected static function getInstance($publickey = null, $secretkey = null)
     {
-        $resource = new static($publickey, $secretkey); // @phpstan-ignore-line
+        $resource = new static($publickey, $secretkey);
         $className = get_class($resource);
         if (!isset(self::$instances[$className])) {
             static::$instances[$className] = $resource;