diff --git a/Classes/PHPExcel/Cell.php b/Classes/PHPExcel/Cell.php
index 9c76e6c0..796217be 100644
--- a/Classes/PHPExcel/Cell.php
+++ b/Classes/PHPExcel/Cell.php
@@ -649,16 +649,16 @@ class PHPExcel_Cell
 
 		//	We also use the language construct isset() rather than the more costly strlen() function to match the length of $pString
 		//		for improved performance
-		if (isset($pString[0])) {
-			if (!isset($pString[1])) {
+		if (isset($pString{0})) {
+			if (!isset($pString{1})) {
 				return $_columnLookup[$pString];
-			} elseif(!isset($pString[2])) {
-				return $_columnLookup[$pString[0]] * 26 + $_columnLookup[$pString[1]];
-			} elseif(!isset($pString[3])) {
-				return $_columnLookup[$pString[0]] * 676 + $_columnLookup[$pString[1]] * 26 + $_columnLookup[$pString[2]];
+			} elseif(!isset($pString{2})) {
+				return $_columnLookup[$pString{0}] * 26 + $_columnLookup[$pString{1}];
+			} elseif(!isset($pString{3})) {
+				return $_columnLookup[$pString{0}] * 676 + $_columnLookup[$pString{1}] * 26 + $_columnLookup[$pString{2}];
 			}
 		}
-		throw new Exception("Column string index can not be " . ((isset($pString[0])) ? "longer than 3 characters" : "empty") . ".");
+		throw new Exception("Column string index can not be " . ((isset($pString{0})) ? "longer than 3 characters" : "empty") . ".");
 	}
 
 	/**