diff --git a/src/Microsoft.OpenApi/Writers/OpenApiWriterAnyExtensions.cs b/src/Microsoft.OpenApi/Writers/OpenApiWriterAnyExtensions.cs
index ad25d885e..5e77ef792 100644
--- a/src/Microsoft.OpenApi/Writers/OpenApiWriterAnyExtensions.cs
+++ b/src/Microsoft.OpenApi/Writers/OpenApiWriterAnyExtensions.cs
@@ -51,6 +51,7 @@ public static void WriteAny<T>(this IOpenApiWriter writer, T any) where T : IOpe
             if (any == null)
             {
                 writer.WriteNull();
+                return;
             }
 
             switch (any.AnyKind)