1 files changed, 13 insertions, 1 deletions
diff --git a/container-search/src/main/java/com/yahoo/search/grouping/request/ZCurveXFunction.java b/container-search/src/main/java/com/yahoo/search/grouping/request/ZCurveXFunction.java
index bcd6f2ba71a..5ab057ef8a8 100644
--- a/container-search/src/main/java/com/yahoo/search/grouping/request/ZCurveXFunction.java
+++ b/container-search/src/main/java/com/yahoo/search/grouping/request/ZCurveXFunction.java
@@ -5,14 +5,26 @@ import java.util.Arrays;
 
 /**
  * @author baldersheim
+ * @author bratseth
  */
 public class ZCurveXFunction extends FunctionNode {
+
     /**
      * Constructs a new instance of this class.
      *
      * @param exp The expression to evaluate, must evaluate to a long or long[].
      */
     public ZCurveXFunction(GroupingExpression exp) {
-        super("zcurve.x", Arrays.asList(exp));
+        this(null, null, exp);
+    }
+
+    private ZCurveXFunction(String label, Integer level, GroupingExpression exp) {
+        super("zcurve.x", label, level, Arrays.asList(exp));
     }
+
+    @Override
+    public ZCurveXFunction copy() {
+        return new ZCurveXFunction(getLabel(), getLevelOrNull(), getArg(0).copy());
+    }
+
 }