diff --git a/composer.json b/composer.json
index 5f91a29..379e59e 100644
--- a/composer.json
+++ b/composer.json
@@ -32,7 +32,7 @@
     },
     "require-dev": {
         "bamarni/composer-bin-plugin": "^1.8.1",
-        "phpunit/phpunit": "^8.5.19"
+        "phpunit/phpunit": "^8.5.19 || ^9.5.8"
     },
     "autoload": {
         "psr-4": {
diff --git a/src/ServiceClient.php b/src/ServiceClient.php
index c8118d0..0bfb957 100644
--- a/src/ServiceClient.php
+++ b/src/ServiceClient.php
@@ -121,7 +121,7 @@ public function executeAllAsync($commands, array $options = [])
         }
 
         // Convert the iterator of commands to a generator of promises.
-        $commands = Promise\iter_for($commands);
+        $commands = Promise\Create::iterFor($commands);
         $promises = function () use ($commands) {
             foreach ($commands as $key => $command) {
                 if (!$command instanceof CommandInterface) {
@@ -166,7 +166,7 @@ public function __call($name, array $args)
     private function createCommandHandler()
     {
         return function (CommandInterface $command) {
-            return Promise\coroutine(function () use ($command) {
+            return Promise\Coroutine::of(function () use ($command) {
                 // Prepare the HTTP options.
                 $opts = $command['@http'] ?: [];
                 unset($command['@http']);