diff --git a/DependencyInjection/WBWSMSModeExtension.php b/DependencyInjection/WBWSMSModeExtension.php
index 701e202..156ebbb 100644
--- a/DependencyInjection/WBWSMSModeExtension.php
+++ b/DependencyInjection/WBWSMSModeExtension.php
@@ -37,7 +37,7 @@ class WBWSMSModeExtension extends Extension {
      * {@inheritDoc}
      */
     public function getAlias(): string {
-        return static::EXTENSION_ALIAS;
+        return self::EXTENSION_ALIAS;
     }
 
     /**
diff --git a/EventListener/SMSModeEventListener.php b/EventListener/SMSModeEventListener.php
index f806eac..0d67a1c 100644
--- a/EventListener/SMSModeEventListener.php
+++ b/EventListener/SMSModeEventListener.php
@@ -99,7 +99,7 @@ protected function beforeHandleEvent(): void {
             $requestNormalizer->serialize($authentication);
         } catch (InvalidArgumentException $ex) {
 
-            throw new RuntimeException(static::RUNTIME_EXCEPTION_MESSAGE, 500, $ex);
+            throw new RuntimeException(self::RUNTIME_EXCEPTION_MESSAGE, 500, $ex);
         }
     }