diff --git a/druid-hdrhistogram/src/main/java/org/apache/druid/query/aggregation/sketch/HdrHistogram/HdrHistogramToQuantilePostAggregator.java b/druid-hdrhistogram/src/main/java/org/apache/druid/query/aggregation/sketch/HdrHistogram/HdrHistogramToQuantilePostAggregator.java
index 5b13b90..71c7494 100644
--- a/druid-hdrhistogram/src/main/java/org/apache/druid/query/aggregation/sketch/HdrHistogram/HdrHistogramToQuantilePostAggregator.java
+++ b/druid-hdrhistogram/src/main/java/org/apache/druid/query/aggregation/sketch/HdrHistogram/HdrHistogramToQuantilePostAggregator.java
@@ -2,8 +2,9 @@ package org.apache.druid.query.aggregation.sketch.HdrHistogram;
 
 import com.fasterxml.jackson.annotation.JsonCreator;
 import com.fasterxml.jackson.annotation.JsonProperty;
+import com.google.common.collect.Ordering;
 import com.google.common.collect.Sets;
-import org.HdrHistogram.Histogram;
+import com.google.common.primitives.Longs;
 import org.HdrHistogram.HistogramSketch;
 import org.apache.druid.java.util.common.IAE;
 import org.apache.druid.query.aggregation.AggregatorFactory;
@@ -23,6 +24,14 @@ public class HdrHistogramToQuantilePostAggregator implements PostAggregator {
     private final String fieldName;
     private final float probability;
 
+    static final Comparator COMPARATOR = new Ordering(){
+        @Override
+        public int compare(Object o, Object o1)
+        {
+            return Longs.compare(((Number) o).longValue(), ((Number) o1).longValue());
+        }
+    }.nullsFirst();
+
     @JsonCreator
     public HdrHistogramToQuantilePostAggregator(
             @JsonProperty("name") String name,
@@ -49,13 +58,8 @@ public class HdrHistogramToQuantilePostAggregator implements PostAggregator {
     }
 
     @Override
-    public Comparator getComparator() {
-        return new Comparator<Long>(){
-            @Override
-            public int compare(final Long a, final Long b){
-                return Long.compare(a, b);
-            }
-        };
+    public Comparator<Long> getComparator() {
+        return COMPARATOR;
     }
 
     @Nullable