diff --git a/uploadservice/src/main/java/net/gotev/uploadservice/UploadTask.java b/uploadservice/src/main/java/net/gotev/uploadservice/UploadTask.java
index <HASH>..<HASH> 100644
--- a/uploadservice/src/main/java/net/gotev/uploadservice/UploadTask.java
+++ b/uploadservice/src/main/java/net/gotev/uploadservice/UploadTask.java
@@ -47,7 +47,7 @@ public abstract class UploadTask implements Runnable {
     /**
      * Contains the absolute local path of the successfully uploaded files.
      */
-    private List<String> successfullyUploadedFiles = new ArrayList<>();
+    private final List<String> successfullyUploadedFiles = new ArrayList<>();
 
     /**
      * Flag indicating if the operation should continue or is cancelled. You should never
successfullyUploadedFiles list is now final, as it's created only once and never re-assigned.