diff --git a/src/cloudflare/internal/workflows-api.ts b/src/cloudflare/internal/workflows-api.ts
index 5393bc04452..55a3114710a 100644
--- a/src/cloudflare/internal/workflows-api.ts
+++ b/src/cloudflare/internal/workflows-api.ts
@@ -3,13 +3,6 @@
 //     https://opensource.org/licenses/Apache-2.0
 
 export class NonRetryableError extends Error {
-  // `__brand` is how engine validates that the user returned a `NonRetryableError`
-  // imported from "cloudflare:workflows"
-  // This enables them to extend NonRetryableError for their own Errors
-  // as well by overriding name
-  // Private fields are not serialized over RPC
-  public readonly __brand: string = 'NonRetryableError';
-
   public constructor(message: string, name = 'NonRetryableError') {
     super(message);
     this.name = name;
diff --git a/types/defines/workflows.d.ts b/types/defines/workflows.d.ts
index 6858b5e0fab..db83df77450 100644
--- a/types/defines/workflows.d.ts
+++ b/types/defines/workflows.d.ts
@@ -1,13 +1,9 @@
-/**
- * NonRetryableError allows for a user to throw a fatal error
- * that makes a Workflow instance fail immediately without triggering a retry
- */
 declare module "cloudflare:workflows" {
-  export abstract class NonRetryableError extends Error {
-    /**
-     * `__brand` is used to differentiate between `NonRetryableError` and `Error`
-     * and is omitted from the constructor because users should not set it
-     */
+  /**
+   * NonRetryableError allows for a user to throw a fatal error
+   * that makes a Workflow instance fail immediately without triggering a retry
+   */
+  export class NonRetryableError extends Error {
     public constructor(message: string, name?: string);
   }
 }