diff --git a/src/lib/ServerCallWriter.php b/src/lib/ServerCallWriter.php
index aceb20c..50075bf 100644
--- a/src/lib/ServerCallWriter.php
+++ b/src/lib/ServerCallWriter.php
@@ -81,7 +81,7 @@ public function finish(
 
     private function addSendInitialMetadataOpIfNotSent(
         array &$batch,
-        array $initialMetadata = null
+        $initialMetadata = null
     ) {
         if (!$this->initialMetadataSent_) {
             $batch[OP_SEND_INITIAL_METADATA] = $initialMetadata ?? [];
diff --git a/src/lib/Status.php b/src/lib/Status.php
index add208f..5acc56d 100644
--- a/src/lib/Status.php
+++ b/src/lib/Status.php
@@ -32,7 +32,7 @@
  */
 class Status
 {
-    public static function status(int $code, string $details, array $metadata = null): array
+    public static function status(int $code, string $details, $metadata = null): array
     {
         $status = [
             'code' => $code,
@@ -44,7 +44,7 @@ public static function status(int $code, string $details, array $metadata = null
         return $status;
     }
 
-    public static function ok(array $metadata = null): array
+    public static function ok($metadata = null): array
     {
         return Status::status(STATUS_OK, 'OK', $metadata);
     }