diff --git a/lib/promise-adapter/src/Adapter/WebonyxGraphQLSyncPromiseAdapter.php b/lib/promise-adapter/src/Adapter/WebonyxGraphQLSyncPromiseAdapter.php
index 7fb5eaa..dd60566 100644
--- a/lib/promise-adapter/src/Adapter/WebonyxGraphQLSyncPromiseAdapter.php
+++ b/lib/promise-adapter/src/Adapter/WebonyxGraphQLSyncPromiseAdapter.php
@@ -32,7 +32,7 @@ class WebonyxGraphQLSyncPromiseAdapter implements PromiseAdapterInterface
 
     public function __construct(?SyncPromiseAdapter $webonyxPromiseAdapter = null)
     {
-        $webonyxPromiseAdapter = $webonyxPromiseAdapter?:new SyncPromiseAdapter();
+        $webonyxPromiseAdapter = $webonyxPromiseAdapter?:new \Overblog\DataLoader\Promise\Adapter\Webonyx\GraphQL\SyncPromiseAdapter();
         $this->setWebonyxPromiseAdapter($webonyxPromiseAdapter);
     }
 
diff --git a/src/DataLoader.php b/src/DataLoader.php
index a016c68..74526de 100644
--- a/src/DataLoader.php
+++ b/src/DataLoader.php
@@ -355,18 +355,11 @@ function ($values) use ($keys, $queue) {
                         sprintf('not return a Promise of an Array: %s.', gettype($values))
                     );
                 }
-                if (count($values) !== count($keys)) {
-                    throw new \RuntimeException(
-                        'DataLoader must be constructed with a function which accepts ' .
-                        'Array<key> and returns Promise<Array<value>>, but the function did ' .
-                        'not return a Promise of an Array of the same length as the Array of keys.'
-                    );
-                }
 
                 // Step through the values, resolving or rejecting each Promise in the
                 // loaded queue.
-                foreach ($queue as $index => $data) {
-                    $value = $values[$index];
+                foreach ($queue as $data) {
+                    $value = $values[$data['key']] ?? null;
                     if ($value instanceof \Throwable) {
                         $data['reject']($value);
                     } else {
diff --git a/src/Promise/Adapter/Webonyx/GraphQL/SyncPromiseAdapter.php b/src/Promise/Adapter/Webonyx/GraphQL/SyncPromiseAdapter.php
index da42184..314ae51 100644
--- a/src/Promise/Adapter/Webonyx/GraphQL/SyncPromiseAdapter.php
+++ b/src/Promise/Adapter/Webonyx/GraphQL/SyncPromiseAdapter.php
@@ -11,9 +11,17 @@
 
 namespace Overblog\DataLoader\Promise\Adapter\Webonyx\GraphQL;
 
+use Countable;
+use Ds\Map;
+use Exception;
+use GraphQL\Error\InvariantViolation;
+use GraphQL\Executor\Promise\Adapter\SyncPromise;
 use GraphQL\Executor\Promise\Adapter\SyncPromiseAdapter as BaseSyncPromiseAdapter;
 use GraphQL\Executor\Promise\Promise;
 use Overblog\DataLoader\DataLoader;
+use Throwable;
+use function assert;
+use function is_array;
 
 class SyncPromiseAdapter extends BaseSyncPromiseAdapter
 {
@@ -26,4 +34,44 @@ protected function onWait(Promise $promise): void
     {
         DataLoader::await();
     }
+
+    /** @throws InvariantViolation */
+    public function all(iterable $promisesOrValues): Promise
+    {
+        assert(is_countable($promisesOrValues));
+
+        $all = new SyncPromise();
+
+        $total = count($promisesOrValues);
+        $count = 0;
+        /** @var Map<K, V|null> $result */
+        $result = new Map();
+
+        $resolveAllWhenFinished = function () use (&$count, &$total, $all, &$result, $promisesOrValues): void {
+            if ($count === $total) {
+                $all->resolve(is_array($promisesOrValues) ? $result->toArray() : $result);
+            }
+        };
+
+        foreach ($promisesOrValues as $index => $promiseOrValue) {
+            if ($promiseOrValue instanceof Promise) {
+                $result->put($index, null);
+                $promiseOrValue->then(
+                    static function ($value) use ($result, $index, &$count, &$resolveAllWhenFinished): void {
+                        $result->put($index, $value);
+                        ++$count;
+                        $resolveAllWhenFinished();
+                    },
+                    static fn (Throwable $reason): SyncPromise => $all->reject($reason)
+                );
+            } else {
+                $result->put($index, $promiseOrValue);
+                ++$count;
+            }
+        }
+
+        $resolveAllWhenFinished();
+
+        return new Promise($all, $this);
+    }
 }