diff --git a/src/Spout/Writer/Common/Sheet.php b/src/Spout/Writer/Common/Sheet.php
index 2c0d1f2..66e4d57 100644
--- a/src/Spout/Writer/Common/Sheet.php
+++ b/src/Spout/Writer/Common/Sheet.php
@@ -3,6 +3,7 @@
 namespace Box\Spout\Writer\Common;
 
 use Box\Spout\Common\Helper\StringHelper;
+use Box\Spout\Writer\Common\Internal\WorkbookInterface;
 use Box\Spout\Writer\Exception\InvalidSheetNameException;
 
 /**
@@ -21,8 +22,8 @@ class Sheet
     /** @var array Invalid characters that cannot be contained in the sheet name */
     private static $INVALID_CHARACTERS_IN_SHEET_NAME = ['\\', '/', '?', '*', ':', '[', ']'];
 
-    /** @var array Associative array [SHEET_INDEX] => [SHEET_NAME] keeping track of sheets' name to enforce uniqueness */
-    protected static $SHEETS_NAME_USED = [];
+    /** @var \Box\Spout\Writer\Common\Internal\WorkbookInterface reference to Workbook this sheet is a part of */
+    protected $workbook;
 
     /** @var int Index of the sheet, based on order in the workbook (zero-based) */
     protected $index;
@@ -36,9 +37,10 @@ class Sheet
     /**
      * @param int $sheetIndex Index of the sheet, based on order in the workbook (zero-based)
      */
-    public function __construct($sheetIndex)
+    public function __construct($sheetIndex, WorkbookInterface $wb)
     {
         $this->index = $sheetIndex;
+		$this->workbook = $wb;
         $this->stringHelper = new StringHelper();
         $this->setName(self::DEFAULT_SHEET_NAME_PREFIX . ($sheetIndex + 1));
     }
@@ -71,14 +73,13 @@ class Sheet
      * @api
      * @param string $name Name of the sheet
      * @return Sheet
-     * @throws \Box\Spout\Writer\Exception\InvalidSheetNameException If the sheet's name is invalid.
+     * @throws InvalidSheetNameException If the sheet's name is invalid.
      */
     public function setName($name)
     {
         $this->throwIfNameIsInvalid($name);
 
         $this->name = $name;
-        self::$SHEETS_NAME_USED[$this->index] = $name;
 
         return $this;
     }
@@ -89,7 +90,7 @@ class Sheet
      *
      * @param string $name
      * @return void
-     * @throws \Box\Spout\Writer\Exception\InvalidSheetNameException If the sheet's name is invalid.
+     * @throws InvalidSheetNameException If the sheet's name is invalid.
      */
     protected function throwIfNameIsInvalid($name)
     {
@@ -163,11 +164,12 @@ class Sheet
      */
     protected function isNameUnique($name)
     {
-        foreach (self::$SHEETS_NAME_USED as $sheetIndex => $sheetName) {
-            if ($sheetIndex !== $this->index && $sheetName === $name) {
-                return false;
-            }
-        }
+		foreach ($this->workbook->getWorksheets() as $sheetIndex => $worksheet) {
+			$sheet = $worksheet->getExternalSheet();
+			if ($sheetIndex !== $this->index && $sheet->getName() === $name) {
+				return false;
+			}
+		}
 
         return true;
     }
diff --git a/src/Spout/Writer/ODS/Internal/Workbook.php b/src/Spout/Writer/ODS/Internal/Workbook.php
index ce24f2f..880f276 100644
--- a/src/Spout/Writer/ODS/Internal/Workbook.php
+++ b/src/Spout/Writer/ODS/Internal/Workbook.php
@@ -69,7 +69,7 @@ class Workbook extends AbstractWorkbook
     public function addNewSheet()
     {
         $newSheetIndex = count($this->worksheets);
-        $sheet = new Sheet($newSheetIndex);
+        $sheet = new Sheet($newSheetIndex, $this);
 
         $sheetsContentTempFolder = $this->fileSystemHelper->getSheetsContentTempFolder();
         $worksheet = new Worksheet($sheet, $sheetsContentTempFolder);
diff --git a/src/Spout/Writer/XLSX/Internal/Workbook.php b/src/Spout/Writer/XLSX/Internal/Workbook.php
index bdf027f..5eba944 100644
--- a/src/Spout/Writer/XLSX/Internal/Workbook.php
+++ b/src/Spout/Writer/XLSX/Internal/Workbook.php
@@ -83,7 +83,7 @@ class Workbook extends AbstractWorkbook
     public function addNewSheet()
     {
         $newSheetIndex = count($this->worksheets);
-        $sheet = new Sheet($newSheetIndex);
+        $sheet = new Sheet($newSheetIndex, $this);
 
         $worksheetFilesFolder = $this->fileSystemHelper->getXlWorksheetsFolder();
         $worksheet = new Worksheet($sheet, $worksheetFilesFolder, $this->sharedStringsHelper, $this->styleHelper, $this->shouldUseInlineStrings);
diff --git a/tests/Spout/Writer/Common/SheetTest.php b/tests/Spout/Writer/Common/SheetTest.php
index 6bee6c6..d91dc06 100644
--- a/tests/Spout/Writer/Common/SheetTest.php
+++ b/tests/Spout/Writer/Common/SheetTest.php
@@ -2,19 +2,25 @@
 
 namespace Box\Spout\Writer\Common;
 
+use Box\Spout\Writer\Common\Internal\AbstractWorkbook;
+use Box\Spout\Writer\Common\Internal\WorksheetInterface;
+use PHPUnit_Framework_TestCase;
+
 /**
  * Class SheetTest
  *
  * @package Box\Spout\Writer\Common
  */
-class SheetTest extends \PHPUnit_Framework_TestCase
+class SheetTest extends PHPUnit_Framework_TestCase
 {
     /**
      * @return void
      */
     public function testGetSheetName()
     {
-        $sheets = [new Sheet(0), new Sheet(1)];
+        $workbook = new SheetTestWorkbook();
+
+        $sheets = [$workbook->addNewSheet(), $workbook->addNewSheet()];
 
         $this->assertEquals('Sheet1', $sheets[0]->getName(), 'Invalid name for the first sheet');
         $this->assertEquals('Sheet2', $sheets[1]->getName(), 'Invalid name for the second sheet');
@@ -25,8 +31,10 @@ class SheetTest extends \PHPUnit_Framework_TestCase
      */
     public function testSetSheetNameShouldCreateSheetWithCustomName()
     {
+        $workbook = new SheetTestWorkbook();
+
         $customSheetName = 'CustomName';
-        $sheet = new Sheet(0);
+        $sheet = $workbook->addNewSheet();
         $sheet->setName($customSheetName);
 
         $this->assertEquals($customSheetName, $sheet->getName(), "The sheet name should have been changed to '$customSheetName'");
@@ -63,7 +71,8 @@ class SheetTest extends \PHPUnit_Framework_TestCase
      */
     public function testSetSheetNameShouldThrowOnInvalidName($customSheetName)
     {
-        (new Sheet(0))->setName($customSheetName);
+        $workbook = new SheetTestWorkbook();
+        $workbook->addNewSheet()->setName($customSheetName);
     }
 
     /**
@@ -71,8 +80,9 @@ class SheetTest extends \PHPUnit_Framework_TestCase
      */
     public function testSetSheetNameShouldNotThrowWhenSettingSameNameAsCurrentOne()
     {
+        $workbook = new SheetTestWorkbook();
         $customSheetName = 'Sheet name';
-        $sheet = new Sheet(0);
+        $sheet = $workbook->addNewSheet();
         $sheet->setName($customSheetName);
         $sheet->setName($customSheetName);
     }
@@ -83,12 +93,75 @@ class SheetTest extends \PHPUnit_Framework_TestCase
      */
     public function testSetSheetNameShouldThrowWhenNameIsAlreadyUsed()
     {
+        $workbook = new SheetTestWorkbook();
+
         $customSheetName = 'Sheet name';
 
-        $sheet = new Sheet(0);
+        $sheet = $workbook->addNewSheet();
         $sheet->setName($customSheetName);
 
-        $sheet = new Sheet(1);
+        $sheet = $workbook->addNewSheet();
         $sheet->setName($customSheetName);
     }
 }
+
+class SheetTestWorkbook extends AbstractWorkbook
+{
+	public function __construct()
+	{
+		parent::__construct(false, null);
+	}
+
+	protected function getMaxRowsPerWorksheet()
+	{
+		return 0;
+	}
+
+	protected function getStyleHelper()
+	{
+		return null;
+	}
+
+	public function addNewSheet()
+	{
+        $newSheetIndex = count($this->worksheets);
+        $sheet = new Sheet($newSheetIndex, $this);
+        $this->worksheets[] = new SheetTestWorksheet($sheet);
+        return $sheet;
+	}
+
+	public function close($finalFilePointer)
+	{
+	}
+}
+
+class SheetTestWorksheet implements WorksheetInterface
+{
+	private $sheet;
+
+	public function __construct(Sheet $sheet)
+	{
+		$this->sheet = $sheet;
+	}
+
+	public function addRow($dataRow, $style)
+	{
+
+	}
+
+	public function close()
+	{
+
+	}
+
+	public function getExternalSheet()
+	{
+		return $this->sheet;
+	}
+
+	public function getLastWrittenRowIndex()
+	{
+
+	}
+
+}