diff --git a/solr/core/src/java/org/apache/solr/search/grouping/distributed/shardresultserializer/SearchGroupsResultTransformer.java b/solr/core/src/java/org/apache/solr/search/grouping/distributed/shardresultserializer/SearchGroupsResultTransformer.java
index 6ca58ce..bacacac 100644
--- a/solr/core/src/java/org/apache/solr/search/grouping/distributed/shardresultserializer/SearchGroupsResultTransformer.java
+++ b/solr/core/src/java/org/apache/solr/search/grouping/distributed/shardresultserializer/SearchGroupsResultTransformer.java
@@ -111,7 +111,7 @@
         }
       }
 
-      final Long groupCount = (Long) topGroupsAndGroupCount.get(GROUP_COUNT);
+      final Long groupCount = topGroupsAndGroupCount.get(GROUP_COUNT)==null? null: ((Number) topGroupsAndGroupCount.get(GROUP_COUNT)).longValue();
       result.put(command.getKey(), new SearchGroupsFieldCommandResult(groupCount, searchGroups));
     }
     return result;