diff --git a/sdk_nnbd/lib/cli/wait_for.dart b/sdk_nnbd/lib/cli/wait_for.dart
index de3cce5f3ae..b24fd4dc2c9 100644
--- a/sdk_nnbd/lib/cli/wait_for.dart
+++ b/sdk_nnbd/lib/cli/wait_for.dart
@@ -111,12 +111,12 @@ class _WaitForUtils {
  * subsequent calls block waiting for a condition that is only satisfied when
  * an earlier call returns.
  */
-T? waitFor<T>(Future<T?> future, {Duration? timeout}) {
-  late T? result;
+T waitFor<T>(Future<T> future, {Duration? timeout}) {
+  late T result;
   bool futureCompleted = false;
   Object? error;
   StackTrace? stacktrace;
-  future.then((r) {
+  future.then((T r) {
     futureCompleted = true;
     result = r;
   }, onError: (e, st) {