diff --git a/src/Spout/Writer/XLSX/Internal/Worksheet.php b/src/Spout/Writer/XLSX/Internal/Worksheet.php
index b78748c..3ffd97b 100644
--- a/src/Spout/Writer/XLSX/Internal/Worksheet.php
+++ b/src/Spout/Writer/XLSX/Internal/Worksheet.php
@@ -146,7 +146,7 @@ EOD;
                     $cellXML .= ' t="s"><v>' . $sharedStringId . '</v></c>';
                 }
             } else if (CellHelper::isBoolean($cellValue)) {
-                $cellXML .= ' t="b"><v>' . $cellValue . '</v></c>';
+                    $cellXML .= ' t="b"><v>' . intval($cellValue) . '</v></c>';
             } else if (CellHelper::isNumeric($cellValue)) {
                 $cellXML .= '><v>' . $cellValue . '</v></c>';
             } else if (empty($cellValue)) {