diff --git a/ts/00_commitinfo_data.ts b/ts/00_commitinfo_data.ts
index 1e46a0f..dcb37a0 100644
--- a/ts/00_commitinfo_data.ts
+++ b/ts/00_commitinfo_data.ts
@@ -3,6 +3,6 @@
  */
 export const commitinfo = {
   name: '@pushrocks/smartpromise',
-  version: '4.0.1',
+  version: '4.0.2',
   description: 'simple promises and Deferred constructs'
 }
diff --git a/ts/smartpromise.classes.deferred.ts b/ts/smartpromise.classes.deferred.ts
index 1517094..37f121c 100644
--- a/ts/smartpromise.classes.deferred.ts
+++ b/ts/smartpromise.classes.deferred.ts
@@ -14,6 +14,12 @@ export class Deferred<T> {
   public reject: IReject;
   public status: TDeferredStatus;
   public claimed = false;
+  public claim() {
+    if (this.claimed) {
+      throw new Error('Deferred already claimed');
+    }
+    this.claimed = true;
+  }
 
   public startedAt: number;
   public stoppedAt: number;