diff --git a/modules/aggs-matrix-stats/src/main/java/org/elasticsearch/search/aggregations/matrix/stats/RunningStats.java b/modules/aggs-matrix-stats/src/main/java/org/elasticsearch/search/aggregations/matrix/stats/RunningStats.java
index 1be3279e8ea..15fe158498c 100644
--- a/modules/aggs-matrix-stats/src/main/java/org/elasticsearch/search/aggregations/matrix/stats/RunningStats.java
+++ b/modules/aggs-matrix-stats/src/main/java/org/elasticsearch/search/aggregations/matrix/stats/RunningStats.java
@@ -82,19 +82,28 @@ public class RunningStats implements Writeable, Cloneable {
         // read doc count
         docCount = (Long)in.readGenericValue();
         // read fieldSum
-        fieldSum = (HashMap<String, Double>)in.readGenericValue();
+        fieldSum = convertIfNeeded((Map<String, Double>)in.readGenericValue());
         // counts
-        counts = (HashMap<String, Long>)in.readGenericValue();
+        counts = convertIfNeeded((Map<String, Long>)in.readGenericValue());
         // means
-        means = (HashMap<String, Double>)in.readGenericValue();
+        means = convertIfNeeded((Map<String, Double>)in.readGenericValue());
         // variances
-        variances = (HashMap<String, Double>)in.readGenericValue();
+        variances = convertIfNeeded((Map<String, Double>)in.readGenericValue());
         // skewness
-        skewness = (HashMap<String, Double>)in.readGenericValue();
+        skewness = convertIfNeeded((Map<String, Double>)in.readGenericValue());
         // kurtosis
-        kurtosis = (HashMap<String, Double>)in.readGenericValue();
+        kurtosis = convertIfNeeded((Map<String, Double>)in.readGenericValue());
         // read covariances
-        covariances = (HashMap<String, HashMap<String, Double>>)in.readGenericValue();
+        covariances = convertIfNeeded((Map<String, HashMap<String, Double>>)in.readGenericValue());
+    }
+
+    // Convert Map to HashMap if it isn't
+    private static <K, V> HashMap<K, V> convertIfNeeded(Map<K,V> map) {
+        if (map instanceof HashMap) {
+            return (HashMap<K, V>) map;
+        } else {
+            return new HashMap<>(map);
+        }
     }
 
     @Override
diff --git a/server/src/main/java/org/elasticsearch/index/query/InnerHitBuilder.java b/server/src/main/java/org/elasticsearch/index/query/InnerHitBuilder.java
index d72134198b8..1db66f1d8ad 100644
--- a/server/src/main/java/org/elasticsearch/index/query/InnerHitBuilder.java
+++ b/server/src/main/java/org/elasticsearch/index/query/InnerHitBuilder.java
@@ -365,7 +365,7 @@ public final class InnerHitBuilder implements Writeable, ToXContentObject {
      * Adds a field to load from the docvalue and return.
      */
     public InnerHitBuilder addDocValueField(String field, String format) {
-        if (docValueFields == null) {
+        if (docValueFields == null || docValueFields.isEmpty() == true) {
             docValueFields = new ArrayList<>();
         }
         docValueFields.add(new FieldAndFormat(field, format));