diff --git a/PHPExcel/PHPExcel/Worksheet/AutoFilter.php b/PHPExcel/PHPExcel/Worksheet/AutoFilter.php
index 03055e1..abde9ad 100755
--- a/PHPExcel/PHPExcel/Worksheet/AutoFilter.php
+++ b/PHPExcel/PHPExcel/Worksheet/AutoFilter.php
@@ -726,7 +726,7 @@ class PHPExcel_Worksheet_AutoFilter
 							);
 						} else {
 							//	Date based
-							if ($dynamicRuleType{0} == 'M' || $dynamicRuleType{0} == 'Q') {
+							if ($dynamicRuleType[0] == 'M' || $dynamicRuleType[0] == 'Q') {
 								//	Month or Quarter
 								sscanf($dynamicRuleType,'%[A-Z]%d', $periodType, $period);
 								if ($periodType == 'M') {