diff --git a/.stats.yml b/.stats.yml
index 70f28c76..150fc433 100644
--- a/.stats.yml
+++ b/.stats.yml
@@ -1,2 +1,2 @@
 configured_endpoints: 9
-openapi_spec_url: https://storage.googleapis.com/stainless-sdk-openapi-specs/anthropic-c7baafa4b7d58ae2b830c0d5b89248e98421c8a7cf135b7e62e6e215fa94c7f4.yml
+openapi_spec_url: https://storage.googleapis.com/stainless-sdk-openapi-specs/anthropic-b629ddf1f1f1473462fc9bdb605abd5b7be51c3ba91c34750cd46e8404aec356.yml
diff --git a/src/resources/beta/messages/batches.ts b/src/resources/beta/messages/batches.ts
index 57e4c91c..0a1da3a1 100644
--- a/src/resources/beta/messages/batches.ts
+++ b/src/resources/beta/messages/batches.ts
@@ -23,7 +23,7 @@ export class Batches extends APIResource {
       body,
       ...options,
       headers: {
-        'anthropic-beta': betas != null ? betas.toString() : 'message-batches-2024-09-24',
+        'anthropic-beta': [...(betas ?? []), 'message-batches-2024-09-24'].toString(),
         ...options?.headers,
       },
     });
@@ -52,7 +52,7 @@ export class Batches extends APIResource {
     return this._client.get(`/v1/messages/batches/${messageBatchId}?beta=true`, {
       ...options,
       headers: {
-        'anthropic-beta': betas != null ? betas.toString() : 'message-batches-2024-09-24',
+        'anthropic-beta': [...(betas ?? []), 'message-batches-2024-09-24'].toString(),
         ...options?.headers,
       },
     });
@@ -78,7 +78,7 @@ export class Batches extends APIResource {
       query,
       ...options,
       headers: {
-        'anthropic-beta': betas != null ? betas.toString() : 'message-batches-2024-09-24',
+        'anthropic-beta': [...(betas ?? []), 'message-batches-2024-09-24'].toString(),
         ...options?.headers,
       },
     });
@@ -106,7 +106,7 @@ export class Batches extends APIResource {
     return this._client.post(`/v1/messages/batches/${messageBatchId}/cancel?beta=true`, {
       ...options,
       headers: {
-        'anthropic-beta': betas != null ? betas.toString() : 'message-batches-2024-09-24',
+        'anthropic-beta': [...(betas ?? []), 'message-batches-2024-09-24'].toString(),
         ...options?.headers,
       },
     });
@@ -149,7 +149,7 @@ export class Batches extends APIResource {
       .get(batch.results_url, {
         ...options,
         headers: {
-          'anthropic-beta': betas != null ? betas.toString() : 'message-batches-2024-09-24',
+          'anthropic-beta': [...(betas ?? []), 'message-batches-2024-09-24'].toString(),
           ...options?.headers,
         },
         __binaryResponse: true,
diff --git a/src/resources/beta/prompt-caching/messages.ts b/src/resources/beta/prompt-caching/messages.ts
index e2295e0b..a1b4c110 100644
--- a/src/resources/beta/prompt-caching/messages.ts
+++ b/src/resources/beta/prompt-caching/messages.ts
@@ -39,7 +39,7 @@ export class Messages extends APIResource {
       timeout: (this._client as any)._options.timeout ?? 600000,
       ...options,
       headers: {
-        'anthropic-beta': betas != null ? betas.toString() : 'prompt-caching-2024-07-31',
+        'anthropic-beta': [...(betas ?? []), 'prompt-caching-2024-07-31'].toString(),
         ...options?.headers,
       },
       stream: params.stream ?? false,