diff --git a/Classes/PHPExcel/Calculation/LookupRef.php b/Classes/PHPExcel/Calculation/LookupRef.php
index c3363f1..96c7da2 100644
--- a/Classes/PHPExcel/Calculation/LookupRef.php
+++ b/Classes/PHPExcel/Calculation/LookupRef.php
@@ -316,9 +316,9 @@ class PHPExcel_Calculation_LookupRef {
 			if (strpos($cellAddress,'!') !== FALSE) {
 				list($sheetName, $cellAddress) = explode('!',$cellAddress);
 				$sheetName = trim($sheetName, "'");
-				$pSheet = $pCell->getParent()->getParent()->getSheetByName($sheetName);
+				$pSheet = $pCell->getWorksheet()->getParent()->getSheetByName($sheetName);
 			} else {
-				$pSheet = $pCell->getParent();
+				$pSheet = $pCell->getWorksheet();
 			}
 
 			return PHPExcel_Calculation::getInstance()->extractNamedRange($cellAddress, $pSheet, FALSE);
@@ -327,9 +327,9 @@ class PHPExcel_Calculation_LookupRef {
 		if (strpos($cellAddress,'!') !== FALSE) {
 			list($sheetName,$cellAddress) = explode('!',$cellAddress);
 			$sheetName = trim($sheetName, "'");
-			$pSheet = $pCell->getParent()->getParent()->getSheetByName($sheetName);
+			$pSheet = $pCell->getWorksheet()->getParent()->getSheetByName($sheetName);
 		} else {
-			$pSheet = $pCell->getParent();
+			$pSheet = $pCell->getWorksheet();
 		}
 
 		return PHPExcel_Calculation::getInstance()->extractCellRange($cellAddress, $pSheet, FALSE);
@@ -421,9 +421,9 @@ class PHPExcel_Calculation_LookupRef {
 		}
 
 		if ($sheetName !== NULL) {
-			$pSheet = $pCell->getParent()->getParent()->getSheetByName($sheetName);
+			$pSheet = $pCell->getWorksheet()->getParent()->getSheetByName($sheetName);
 		} else {
-			$pSheet = $pCell->getParent();
+			$pSheet = $pCell->getWorksheet();
 		}
 
 		return PHPExcel_Calculation::getInstance()->extractCellRange($cellAddress, $pSheet, False);
diff --git a/Classes/PHPExcel/Cell.php b/Classes/PHPExcel/Cell.php
index 6664e64..2cafff3 100644
--- a/Classes/PHPExcel/Cell.php
+++ b/Classes/PHPExcel/Cell.php
@@ -469,7 +469,7 @@ class PHPExcel_Cell
 	/**
 	 *	Get parent worksheet
 	 *
-	 *	@return PHPExcel_Worksheet
+	 *	@return PHPExcel_CachedObjectStorage_CacheBase
 	 */
 	public function getParent() {
 		return $this->_parent;