diff --git a/src/PhpSpreadsheet/Cell/StringValueBinder.php b/src/PhpSpreadsheet/Cell/StringValueBinder.php
index a005f1a7..1b607692 100644
--- a/src/PhpSpreadsheet/Cell/StringValueBinder.php
+++ b/src/PhpSpreadsheet/Cell/StringValueBinder.php
@@ -9,22 +9,22 @@ use PhpOffice\PhpSpreadsheet\Shared\StringHelper;
 class StringValueBinder implements IValueBinder
 {
     /**
-     * @var bool $convertNull
+     * @var bool
      */
     protected $convertNull = true;
 
     /**
-     * @var bool $convertBoolean
+     * @var bool
      */
     protected $convertBoolean = true;
 
     /**
-     * @var bool $convertNumeric
+     * @var bool
      */
     protected $convertNumeric = true;
 
     /**
-     * @var bool $convertFormula
+     * @var bool
      */
     protected $convertFormula = true;
 
diff --git a/tests/PhpSpreadsheetTests/Cell/StringValueBinderTest.php b/tests/PhpSpreadsheetTests/Cell/StringValueBinderTest.php
index 2455a4e9..d772241f 100644
--- a/tests/PhpSpreadsheetTests/Cell/StringValueBinderTest.php
+++ b/tests/PhpSpreadsheetTests/Cell/StringValueBinderTest.php
@@ -15,8 +15,10 @@ class StringValueBinderTest extends TestCase
 {
     /**
      * @param mixed $expectedValue
+     *
+     * @return Cell&MockObject
      */
-    protected function createCellStub($expectedValue, string $expectedDataType, bool $quotePrefix = false): Cell
+    protected function createCellStub($expectedValue, string $expectedDataType, bool $quotePrefix = false): MockObject
     {
         /** @var Style&MockObject $styleStub */
         $styleStub = $this->getMockBuilder(Style::class)