diff --git a/tests/PhpSpreadsheetTests/Cell/HyperlinkTest.php b/tests/PhpSpreadsheetTests/Cell/HyperlinkTest.php
index 74f403d1..11d8c00c 100644
--- a/tests/PhpSpreadsheetTests/Cell/HyperlinkTest.php
+++ b/tests/PhpSpreadsheetTests/Cell/HyperlinkTest.php
@@ -24,7 +24,7 @@ class HyperlinkTest extends TestCase
 
         $testInstance = new Hyperlink($initialUrlValue);
         $result = $testInstance->setUrl($newUrlValue);
-        self::assertTrue($result instanceof Hyperlink);
+        self::assertInstanceOf(Hyperlink::class, $result);
 
         $result = $testInstance->getUrl();
         self::assertEquals($newUrlValue, $result);
@@ -47,7 +47,7 @@ class HyperlinkTest extends TestCase
 
         $testInstance = new Hyperlink(null, $initialTooltipValue);
         $result = $testInstance->setTooltip($newTooltipValue);
-        self::assertTrue($result instanceof Hyperlink);
+        self::assertInstanceOf(Hyperlink::class, $result);
 
         $result = $testInstance->getTooltip();
         self::assertEquals($newTooltipValue, $result);
diff --git a/tests/PhpSpreadsheetTests/Chart/DataSeriesValuesTest.php b/tests/PhpSpreadsheetTests/Chart/DataSeriesValuesTest.php
index 47c018ad..2231bc26 100644
--- a/tests/PhpSpreadsheetTests/Chart/DataSeriesValuesTest.php
+++ b/tests/PhpSpreadsheetTests/Chart/DataSeriesValuesTest.php
@@ -19,7 +19,7 @@ class DataSeriesValuesTest extends TestCase
 
         foreach ($dataTypeValues as $dataTypeValue) {
             $result = $testInstance->setDataType($dataTypeValue);
-            self::assertTrue($result instanceof DataSeriesValues);
+            self::assertInstanceOf(DataSeriesValues::class, $result);
         }
     }
 
diff --git a/tests/PhpSpreadsheetTests/Chart/LayoutTest.php b/tests/PhpSpreadsheetTests/Chart/LayoutTest.php
index 05166e8e..9ae80460 100644
--- a/tests/PhpSpreadsheetTests/Chart/LayoutTest.php
+++ b/tests/PhpSpreadsheetTests/Chart/LayoutTest.php
@@ -14,7 +14,7 @@ class LayoutTest extends TestCase
         $testInstance = new Layout();
 
         $result = $testInstance->setLayoutTarget($LayoutTargetValue);
-        self::assertTrue($result instanceof Layout);
+        self::assertInstanceOf(Layout::class, $result);
     }
 
     public function testGetLayoutTarget()