diff --git a/server/src/main/java/org/elasticsearch/search/aggregations/bucket/histogram/InternalAutoDateHistogram.java b/server/src/main/java/org/elasticsearch/search/aggregations/bucket/histogram/InternalAutoDateHistogram.java
index f10318de02e..3be59c0c1f7 100644
--- a/server/src/main/java/org/elasticsearch/search/aggregations/bucket/histogram/InternalAutoDateHistogram.java
+++ b/server/src/main/java/org/elasticsearch/search/aggregations/bucket/histogram/InternalAutoDateHistogram.java
@@ -526,6 +526,9 @@ public final class InternalAutoDateHistogram extends
         if (buckets.size() > targetBuckets) {
             for (int interval : roundingInfo.innerIntervals) {
                 int resultingBuckets = buckets.size() / interval;
+                if (buckets.size() % interval != 0) {
+                    resultingBuckets++;
+                }
                 if (resultingBuckets <= targetBuckets) {
                     return mergeConsecutiveBuckets(buckets, interval, roundingIdx, roundingInfo, reduceContext);
                 }
diff --git a/server/src/test/java/org/elasticsearch/search/aggregations/bucket/histogram/InternalAutoDateHistogramTests.java b/server/src/test/java/org/elasticsearch/search/aggregations/bucket/histogram/InternalAutoDateHistogramTests.java
index bc4c84282b2..57020901aae 100644
--- a/server/src/test/java/org/elasticsearch/search/aggregations/bucket/histogram/InternalAutoDateHistogramTests.java
+++ b/server/src/test/java/org/elasticsearch/search/aggregations/bucket/histogram/InternalAutoDateHistogramTests.java
@@ -108,10 +108,7 @@ public class InternalAutoDateHistogramTests extends InternalMultiBucketAggregati
         assertThat(result, equalTo(2));
     }
 
-
-    @Override
-    @AwaitsFix(bugUrl = "https://github.com/elastic/elasticsearch/issues/39497")
-    // TODO: When resolving the above AwaitsFix, just delete this override. Method is only overriden to apply the annotation.
+    
     public void testReduceRandom() {
         super.testReduceRandom();
     }