diff --git a/src/main/java/org/ids_mannheim/SlidingWindowQueue.java b/src/main/java/org/ids_mannheim/SlidingWindowQueue.java
index d54306c..b5225e3 100644
--- a/src/main/java/org/ids_mannheim/SlidingWindowQueue.java
+++ b/src/main/java/org/ids_mannheim/SlidingWindowQueue.java
@@ -19,7 +19,7 @@
     public boolean add(String k) {
         boolean r = super.add(k);
         if (size() == maxSize) {
-            this.flush.accept(String.join(" ", this), fold);
+            this.flush.accept(String.join("\t", this));
             remove(0);
         }
         return r;