diff --git a/src/Protocol/Imap.php b/src/Protocol/Imap.php
index a92de0b4..cd638736 100644
--- a/src/Protocol/Imap.php
+++ b/src/Protocol/Imap.php
@@ -445,7 +445,7 @@ public function capability()
         $response = $this->requestAndResponse('CAPABILITY');
 
         if (! $response) {
-            return $response;
+            return [];
         }
 
         $capabilities = [];