diff --git a/src/spout/SpoutBuilder.php b/src/spout/SpoutBuilder.php
index b655128..dae1e74 100644
--- a/src/spout/SpoutBuilder.php
+++ b/src/spout/SpoutBuilder.php
@@ -175,11 +175,11 @@ class SpoutBuilder extends AbstractBuilder {
       self::apply_params($writer, $writerParams, ref_params_xlsx::WRITER);
       break;
     }
-    $defaultColumnWidth = $writerParams["default_column_width"];
+    $defaultColumnWidth = $writerParams["default_column_width"] ?? null;
     if ($defaultColumnWidth !== null) $writer->setDefaultColumnWidth($defaultColumnWidth);
-    $defaultRowHeight = $writerParams["default_row_height"];
+    $defaultRowHeight = $writerParams["default_row_height"] ?? null;
     if ($defaultRowHeight !== null) $writer->setDefaultRowHeight($defaultRowHeight);
-    $defaultRowStyle = $writerParams["default_row_style"];
+    $defaultRowStyle = $writerParams["default_row_style"] ?? null;
     if ($defaultRowStyle !== null) $writer->setDefaultRowStyle($defaultRowStyle);
     $writer->writeToStream($this->getResource());
 
diff --git a/src/spout/ref_params.php b/src/spout/ref_params.php
index c58f062..7027395 100644
--- a/src/spout/ref_params.php
+++ b/src/spout/ref_params.php
@@ -17,7 +17,7 @@ class ref_params {
 
   const SHEET = [
     "->setName" => ["string"],
-    "-setIsVisible" => ["bool"],
+    "->setIsVisible" => ["bool"],
     "header_style" => self::STYLE,
     "odd_style" => self::STYLE,
     "even_style" => self::STYLE,