diff --git a/presto-main/src/main/java/io/prestosql/operator/aggregation/ParametricAggregation.java b/presto-main/src/main/java/io/prestosql/operator/aggregation/ParametricAggregation.java
index 9f1328fa99ad..d004d83fde1d 100644
--- a/presto-main/src/main/java/io/prestosql/operator/aggregation/ParametricAggregation.java
+++ b/presto-main/src/main/java/io/prestosql/operator/aggregation/ParametricAggregation.java
@@ -50,8 +50,8 @@
 public class ParametricAggregation
         extends SqlAggregationFunction
 {
-    final AggregationHeader details;
-    final ParametricImplementationsGroup<AggregationImplementation> implementations;
+    private final AggregationHeader details;
+    private final ParametricImplementationsGroup<AggregationImplementation> implementations;
 
     public ParametricAggregation(
             Signature signature,