diff --git a/src/Microsoft.OpenApi/Interfaces/IDiagnostic.cs b/src/Microsoft.OpenApi/Interfaces/IDiagnostic.cs
deleted file mode 100644
index e0a07fc3d..000000000
--- a/src/Microsoft.OpenApi/Interfaces/IDiagnostic.cs
+++ /dev/null
@@ -1,12 +0,0 @@
-// Copyright (c) Microsoft Corporation. All rights reserved.
-// Licensed under the MIT license.
-
-namespace Microsoft.OpenApi
-{
-    /// <summary>
-    /// Interface for the entity containing diagnostic information from the reading process.
-    /// </summary>
-    public interface IDiagnostic
-    {
-    }
-}
diff --git a/src/Microsoft.OpenApi/Reader/OpenApiDiagnostic.cs b/src/Microsoft.OpenApi/Reader/OpenApiDiagnostic.cs
index 664dc942b..c66df68eb 100644
--- a/src/Microsoft.OpenApi/Reader/OpenApiDiagnostic.cs
+++ b/src/Microsoft.OpenApi/Reader/OpenApiDiagnostic.cs
@@ -8,7 +8,7 @@ namespace Microsoft.OpenApi.Reader
     /// <summary>
     /// Object containing all diagnostic information related to Open API parsing.
     /// </summary>
-    public class OpenApiDiagnostic : IDiagnostic
+    public class OpenApiDiagnostic
     {
         /// <summary>
         /// List of all errors.
diff --git a/test/Microsoft.OpenApi.Tests/PublicApi/PublicApi.approved.txt b/test/Microsoft.OpenApi.Tests/PublicApi/PublicApi.approved.txt
index 40e9d307f..ab354d5f2 100644
--- a/test/Microsoft.OpenApi.Tests/PublicApi/PublicApi.approved.txt
+++ b/test/Microsoft.OpenApi.Tests/PublicApi/PublicApi.approved.txt
@@ -97,7 +97,6 @@ namespace Microsoft.OpenApi
         public override string Expression { get; }
         public string? Token { get; }
     }
-    public interface IDiagnostic { }
     public interface IMetadataContainer
     {
         System.Collections.Generic.IDictionary<string, object>? Metadata { get; set; }
@@ -1942,7 +1941,7 @@ namespace Microsoft.OpenApi.Reader
     {
         public static System.Text.Json.Nodes.JsonNode? Find(this Microsoft.OpenApi.JsonPointer currentPointer, System.Text.Json.Nodes.JsonNode baseJsonNode) { }
     }
-    public class OpenApiDiagnostic : Microsoft.OpenApi.IDiagnostic
+    public class OpenApiDiagnostic
     {
         public OpenApiDiagnostic() { }
         public System.Collections.Generic.IList<Microsoft.OpenApi.OpenApiError> Errors { get; set; }