diff --git a/src/spout/SpoutBuilder.php b/src/spout/SpoutBuilder.php
index 3d420fa..34258e3 100644
--- a/src/spout/SpoutBuilder.php
+++ b/src/spout/SpoutBuilder.php
@@ -355,6 +355,7 @@ class SpoutBuilder extends AbstractBuilder {
         unset($rowStyle[$method]);
         if ($value !== null) $rowParams[$method] = $value;
       }
+      if ($rowStyle === []) $rowStyle = null;
     }
     $sheetParams = $this->sheetParams;
     $headerStyle = $sheetParams["header_style"] ?? null;