diff --git a/src/Extend/AesCmac.php b/src/Extend/AesCmac.php
index 30d5be0..5b4972d 100644
--- a/src/Extend/AesCmac.php
+++ b/src/Extend/AesCmac.php
@@ -12,7 +12,7 @@
 
 final class AesCmac
 {
-    private const string ALGORITHM = 'AES-128-CBC';
+    private const ALGORITHM = 'AES-128-CBC';
 
     /**
      * Returns a MAC in hex encoding.