diff --git a/.fernignore b/.fernignore
index f184277..53c8943 100644
--- a/.fernignore
+++ b/.fernignore
@@ -1,4 +1,5 @@
 # Specify files that shouldn't be modified by Fern
 src/wrapper
 src/index.ts
-tests/unit/wrapper
\ No newline at end of file
+tests/unit/wrapper
+src/serialization/resources/inboxes/types/UpdateMetadata.ts
\ No newline at end of file
diff --git a/src/serialization/resources/inboxes/types/UpdateMetadata.ts b/src/serialization/resources/inboxes/types/UpdateMetadata.ts
index 5a5dad6..afe5527 100644
--- a/src/serialization/resources/inboxes/types/UpdateMetadata.ts
+++ b/src/serialization/resources/inboxes/types/UpdateMetadata.ts
@@ -8,7 +8,7 @@ import { MetadataValue } from "./MetadataValue.js";
 export const UpdateMetadata: core.serialization.Schema<
     serializers.inboxes.UpdateMetadata.Raw,
     AgentMail.inboxes.UpdateMetadata
-> = core.serialization.record(core.serialization.string(), MetadataValue);
+> = core.serialization.record(core.serialization.string(), MetadataValue.nullable());
 
 export declare namespace UpdateMetadata {
     export type Raw = Record<string, MetadataValue.Raw | null>;