diff --git a/Implab/PromiseT.cs b/Implab/PromiseT.cs
--- a/Implab/PromiseT.cs
+++ b/Implab/PromiseT.cs
@@ -349,18 +349,24 @@ namespace Implab {
 
         public IPromise<T2> Then<T2>(Func<T, T2> mapper, Func<Exception, T2> error, Func<T2> cancel) {
             var promise = new Promise<T2>();
+            if (mapper != null)
+                promise.On(Cancel, PromiseEventType.Cancelled);
             AddHandler(new RemapDescriptor<T2>(mapper, error, cancel, promise));
             return promise;
         }
 
         public IPromise<T2> Then<T2>(Func<T, T2> mapper, Func<Exception, T2> error) {
             var promise = new Promise<T2>();
+            if (mapper != null)
+                promise.On(Cancel, PromiseEventType.Cancelled);
             AddHandler(new RemapDescriptor<T2>(mapper, error, null, promise));
             return promise;
         }
 
         public IPromise<T2> Then<T2>(Func<T, T2> mapper) {
             var promise = new Promise<T2>();
+            if (mapper != null)
+                promise.On(Cancel, PromiseEventType.Cancelled);
             AddHandler(new RemapDescriptor<T2>(mapper, null, null, promise));
             return promise;
         }