diff --git a/core/src/main/java/org/dcache/nfs/v4/CompoundBuilder.java b/core/src/main/java/org/dcache/nfs/v4/CompoundBuilder.java
index 9fff7aa32..dacf92673 100644
--- a/core/src/main/java/org/dcache/nfs/v4/CompoundBuilder.java
+++ b/core/src/main/java/org/dcache/nfs/v4/CompoundBuilder.java
@@ -113,7 +113,8 @@
 
 public class CompoundBuilder {
 
-    private final String NO_TAG = "";
+    private static final String NO_TAG = "";
+
     private String tag = NO_TAG;
     private int minorversion = 1;
     private List<nfs_argop4> ops = new ArrayList<>();