diff --git a/core/src/main/java/pl/project13/core/log/FormattingTuple.java b/core/src/main/java/pl/project13/core/log/FormattingTuple.java
index b5bae414..2d34d0dd 100644
--- a/core/src/main/java/pl/project13/core/log/FormattingTuple.java
+++ b/core/src/main/java/pl/project13/core/log/FormattingTuple.java
@@ -49,7 +49,7 @@
  */
 public class FormattingTuple {
 
-  public static FormattingTuple NULL = new FormattingTuple(null);
+  public static final FormattingTuple NULL = new FormattingTuple(null);
 
   private String message;
   private Throwable throwable;