diff --git a/src/Form.php b/src/Form.php
index 3c6aa865..bf790eb8 100644
--- a/src/Form.php
+++ b/src/Form.php
@@ -165,6 +165,7 @@ private function generateFormEncodedBody(): string
             }
         }
 
+        /** @psalm-suppress InvalidArgument */
         return QueryString::build($pairs, '&', \PHP_QUERY_RFC1738) ?? '';
     }