diff --git a/src/main/java/org/ids_mannheim/TotalNGrams.java b/src/main/java/org/ids_mannheim/TotalNGrams.java
index 0d28c12..408b0a4 100644
--- a/src/main/java/org/ids_mannheim/TotalNGrams.java
+++ b/src/main/java/org/ids_mannheim/TotalNGrams.java
@@ -167,7 +167,9 @@
             logger.info("Writing unsorted frequency table.");
             System.err.println("Writing unsorted frequency table.");
             map.entrySet()
-                    .forEach(entry -> output_stream.println(entry.getKey() + "\t" + Integer.toUnsignedString(entry.getValue().get())));
+                    .forEach(entry -> output_stream.println(new StringBuilder(entry.getKey())
+                            .append('\t')
+                            .append(Integer.toUnsignedString(entry.getValue().get()))));
         } else {
             logger.info("Sorting and writing frequency table.");
             System.err.println("Sorting and writing frequency table.");