diff --git a/packages/bun-types/globals.d.ts b/packages/bun-types/globals.d.ts
index e2ee4699da..92574daa42 100644
--- a/packages/bun-types/globals.d.ts
+++ b/packages/bun-types/globals.d.ts
@@ -3619,6 +3619,11 @@ interface Worker extends EventTarget {
    * Undo a previous `ref()`
    */
   unref(): void;
+
+  /**
+   * Unique per-process thread ID. Main thread ID is always `0`.
+   */
+  readonly threadId: number;
 }
 
 /**