diff --git a/application/source/types/uniquequeue.mjs b/application/source/types/uniquequeue.mjs
index 23ce29631a4f62a68ceb58c8fec9eabaa261fb7c..4d43b391374689cc6664f615669353dde852a659 100644
--- a/application/source/types/uniquequeue.mjs
+++ b/application/source/types/uniquequeue.mjs
@@ -6,12 +6,13 @@
  */
 
 import {Queue} from "./queue.mjs";
+import {internalSymbol} from "../constants.mjs";
 import {validateObject} from "./validate.mjs";
 
 export {UniqueQueue}
 
 /**
- * A UniqueQueue is a queue that contains items only once.
+ * An UniqueQueue is a queue that contains items only once.
  *
  * @license AGPLv3
  * @since 1.4.0
@@ -26,7 +27,9 @@ export {UniqueQueue}
      */
     constructor() {
         super();
-        this.unique = new WeakSet();
+        this[internalSymbol]={
+            unique : new WeakSet()
+        };
     }
 
     /**
@@ -40,8 +43,8 @@ export {UniqueQueue}
 
         validateObject(value);
 
-        if (!this.unique.has(value)) {
-            this.unique.add(value);
+        if (!this[internalSymbol].unique.has(value)) {
+            this[internalSymbol].unique.add(value);
             super.add(value);
         }
 
@@ -55,7 +58,7 @@ export {UniqueQueue}
      */
     clear() {
         super.clear();
-        this.unique = new WeakSet;
+        this[internalSymbol].unique = new WeakSet;
         return this;
     }
 
@@ -71,7 +74,7 @@ export {UniqueQueue}
             return undefined;
         }
         let value = this.data.shift();
-        this.unique.delete(value);
+        this[internalSymbol].unique.delete(value);
         return value;
     }