diff --git a/src/Microsoft.Diagnostics.EventFlow.Outputs.ElasticSearch/ElasticSearchOutput.cs b/src/Microsoft.Diagnostics.EventFlow.Outputs.ElasticSearch/ElasticSearchOutput.cs
index dd6f31e..62e0d9f 100644
--- a/src/Microsoft.Diagnostics.EventFlow.Outputs.ElasticSearch/ElasticSearchOutput.cs
+++ b/src/Microsoft.Diagnostics.EventFlow.Outputs.ElasticSearch/ElasticSearchOutput.cs
@@ -36,7 +36,7 @@ public class ElasticSearchOutput : IOutput
 
         private enum FormatIndexType {QuarterOfYear, WeekOfMonth, WeekOfYearDoubleDigit, WeekOfYear}
 
-        private class FormatIndex: IComparable<FormatIndex>
+        private class FormatIndex: IComparable<FormatIndex>, IEquatable<FormatIndex>
         {
             public FormatIndex(int index, FormatIndexType formatIndexType)
             {
@@ -54,6 +54,17 @@ public int CompareTo(FormatIndex other)
                 if (Index < other.Index) return 1;
                 return Index > other.Index? -1 : 0;
             }
+
+            public override bool Equals(object obj)
+            {
+                FormatIndex other = obj as FormatIndex;
+                if (other is null) return false;
+                return Index == other.Index;
+            }
+
+            public bool Equals(FormatIndex other) => Index == other.Index;
+
+            public override int GetHashCode() => Index.GetHashCode();
         }
 
         private FormatIndex[] formatIndexes;
diff --git a/src/Microsoft.Diagnostics.EventFlow.Outputs.ElasticSearch/Microsoft.Diagnostics.EventFlow.Outputs.ElasticSearch.csproj b/src/Microsoft.Diagnostics.EventFlow.Outputs.ElasticSearch/Microsoft.Diagnostics.EventFlow.Outputs.ElasticSearch.csproj
index 6860413..4585266 100644
--- a/src/Microsoft.Diagnostics.EventFlow.Outputs.ElasticSearch/Microsoft.Diagnostics.EventFlow.Outputs.ElasticSearch.csproj
+++ b/src/Microsoft.Diagnostics.EventFlow.Outputs.ElasticSearch/Microsoft.Diagnostics.EventFlow.Outputs.ElasticSearch.csproj
@@ -3,7 +3,7 @@
   <PropertyGroup>
     <Description>Provides an output implementation that sends diagnostics data to Elasticsearch.</Description>
     <Copyright>© Microsoft Corporation. All rights reserved.</Copyright>
-    <VersionPrefix>2.7.5</VersionPrefix>
+    <VersionPrefix>2.7.6</VersionPrefix>
     <Authors>Microsoft</Authors>
     <TargetFrameworks>net471;netstandard2.0</TargetFrameworks>
     <AssemblyName>Microsoft.Diagnostics.EventFlow.Outputs.ElasticSearch</AssemblyName>