diff --git a/xlsxwriter.class.php b/xlsxwriter.class.php
index 4b3b65b9d..710996e07 100644
--- a/xlsxwriter.class.php
+++ b/xlsxwriter.class.php
@@ -361,7 +361,7 @@ protected function writeCell(XLSXWriter_BuffererWriter &$file, $row_number, $col
 
 		if (!is_scalar($value) || $value==='') { //objects, array, empty
 			$file->write('<c r="'.$cell_name.'" s="'.$cell_style_idx.'"/>');
-		} elseif (is_string($value) && $value{0}=='='){
+		} elseif (is_string($value) && $value[0]=='='){
 			$file->write('<c r="'.$cell_name.'" s="'.$cell_style_idx.'" t="s"><f>'.self::xmlspecialchars($value).'</f></c>');
 		} elseif ($num_format_type=='n_date') {
 			$file->write('<c r="'.$cell_name.'" s="'.$cell_style_idx.'" t="n"><v>'.intval(self::convert_date_time($value)).'</v></c>');