diff --git a/js/Utility.js b/js/Utility.js
index 503c41a..b7e16fa 100755
--- a/js/Utility.js
+++ b/js/Utility.js
@@ -271,7 +271,7 @@ export default class Utility {
                 : new /** @type {EntityConstructor} */(targetType)(value)
         }
         if (value instanceof Boolean || value instanceof Number || value instanceof String) {
-            value = value.valueOf() // Get the relative primitive value
+            value = /** @type {AnyValue} */(value.valueOf()) // Get the relative primitive value
         }
         return value
     }
diff --git a/js/serialization/Grammar.js b/js/serialization/Grammar.js
index ac38687..022e325 100755
--- a/js/serialization/Grammar.js
+++ b/js/serialization/Grammar.js
@@ -245,7 +245,7 @@ export default class Grammar {
 
     /**
      * @template {IEntity} T
-     * @param {AnyConstructor<T> & EntityConstructor} entityType
+     * @param {(new (...args: any) => T) & EntityConstructor} entityType
      * @param {Boolean | Number} acceptUnknownKeys Number to specify the limit or true, to let it be a reasonable value
      * @returns {Parsimmon.Parser<T>}
      */