diff --git a/packages/eventual-send/src/index.d.ts b/packages/eventual-send/src/index.d.ts
index 0b3064e267..1515391a8e 100644
--- a/packages/eventual-send/src/index.d.ts
+++ b/packages/eventual-send/src/index.d.ts
@@ -257,7 +257,7 @@ interface EProxy {
    * E.when(x, res, rej) is equivalent to
    * HandledPromise.resolve(x).then(res, rej)
    */
-  readonly when: <T, U>(
+  readonly when: <T, U = Awaited<T>>(
     x: T,
     onfulfilled?: (value: Awaited<T>) => ERef<U>,
     onrejected?: (reason: any) => ERef<U>,
diff --git a/packages/eventual-send/src/index.test-d.ts b/packages/eventual-send/src/index.test-d.ts
index 74aca3b523..76630cce35 100644
--- a/packages/eventual-send/src/index.test-d.ts
+++ b/packages/eventual-send/src/index.test-d.ts
@@ -46,3 +46,26 @@ const foo2 = async (a: FarRef<{ bar(): string; baz: number }>) => {
   // @ts-expect-error - calling directly is valid but not yet in the typedef
   a.bar;
 };
+
+// when
+const aPromise = Promise.resolve('a');
+const onePromise = Promise.resolve(1);
+const remoteString: ERef<string> = Promise.resolve('remote');
+E.when(Promise.all([aPromise, onePromise, remoteString])).then(
+  ([str, num, remote]) => {
+    expectType<string>(str);
+    expectType<number>(num);
+    expectType<string>(remote);
+  },
+);
+E.when(
+  Promise.all([aPromise, onePromise, remoteString]),
+  ([str, num, remote]) => {
+    expectType<string>(str);
+    expectType<number>(num);
+    expectType<string>(remote);
+    return { something: 'new' };
+  },
+).then(result => {
+  expectType<{ something: string }>(result);
+});