diff --git a/.gitignore b/.gitignore
index c055246..a4bddd5 100644
--- a/.gitignore
+++ b/.gitignore
@@ -6,3 +6,4 @@
 /vendor
 /composer.lock
 /.php_cs.cache
+/.phpunit.result.cache
diff --git a/.travis.yml b/.travis.yml
index ac931ed..365ee59 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -5,16 +5,16 @@ language: php
 
 matrix:
   include:
-    - php: 7.1
-      env: WITH_CS=true
-    - php: 7.1
-      env: WITH_PHPUNIT=true WITH_COVERAGE=true
     - php: 7.2
       env: WITH_PHPUNIT=true
     - php: 7.3
       env: WITH_PHPUNIT=true
+    - php: 7.3
+      env: WITH_PHPUNIT=true WITH_COVERAGE=true
     - php: 7.4
       env: WITH_PHPUNIT=true
+    - php: 8.0
+      env: WITH_PHPUNIT=true
 
 
 cache:
@@ -42,7 +42,7 @@ before_script:
 script:
   - |
     if [[ "$WITH_CS" == "true" ]]; then
-        vendor/bin/php-cs-fixer fix --config=.php_cs.dist --verbose --diff --dry-run
+        vendor/bin/php-cs-fixer fix --config=.php_cs.dist --verbose --diff --dry-run --diff-format=udiff
     fi
   - |
     if [[ "$WITH_PHPUNIT" == "true" ]]; then
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 8fa35c5..5db0f6e 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -68,7 +68,21 @@ This will add your changes on top of what's already in upstream, minimizing merg
 
 Make sure that all tests are passing before submitting a pull request.
 
-### Step 8: Send the pull request
+### Step 8: Fix code style
+
+Run the following command to check the code style of your changes:
+
+```
+vendor/bin/php-cs-fixer fix --config=.php_cs.dist --verbose --diff --dry-run --diff-format=udiff
+```
+
+This will print a diff of proposed code style changes. To apply these suggestions, run the following command:
+
+```
+vendor/bin/php-cs-fixer fix --config=.php_cs.dist
+```
+
+### Step 9: Send the pull request
 
 Send the pull request from your feature branch to us. Be sure to include a description that lets us know what work you did.
 
diff --git a/README.md b/README.md
index 517f5a4..a9a0a9c 100644
--- a/README.md
+++ b/README.md
@@ -20,7 +20,7 @@ Full documentation can be found at [https://opensource.box.com/spout/](https://o
 
 ## Requirements
 
-* PHP version 7.1 or higher
+* PHP version 7.2 or higher
 * PHP extension `php_zip` enabled
 * PHP extension `php_xmlreader` enabled
 
diff --git a/UPGRADE-3.0.md b/UPGRADE-3.0.md
index 3952443..9b2e370 100644
--- a/UPGRADE-3.0.md
+++ b/UPGRADE-3.0.md
@@ -11,7 +11,7 @@ With the 3.0 version, this is now possible: each cell can have its own style.
 
 Spout 3.0 tries to enforce better typing. For instance, instead of using/returning generic arrays, Spout now makes use of specific `Row` and `Cell` objects that can encapsulate more data such as type, style, value.
 
-Finally, **_Spout 3.0 only supports PHP 7.1 and above_**, as other PHP versions are no longer supported by the community.
+Finally, **_Spout 3.2 only supports PHP 7.2 and above_**, as other PHP versions are no longer supported by the community.
 
 Reader changes
 --------------
diff --git a/composer.json b/composer.json
index 8943469..4d9642b 100644
--- a/composer.json
+++ b/composer.json
@@ -12,12 +12,12 @@
         }
     ],
     "require": {
-        "php": ">=7.1.0",
+        "php": ">=7.2.0",
         "ext-zip": "*",
         "ext-xmlreader" : "*"
     },
     "require-dev": {
-        "phpunit/phpunit": "^7",
+        "phpunit/phpunit": "^8",
         "friendsofphp/php-cs-fixer": "^2"
     },
     "suggest": {
@@ -36,7 +36,7 @@
     },
     "config": {
         "platform": {
-            "php": "7.1"
+            "php": "7.2"
         }
     }
 }
diff --git a/docs/_pages/getting-started.md b/docs/_pages/getting-started.md
index 0004d4d..0e0b336 100755
--- a/docs/_pages/getting-started.md
+++ b/docs/_pages/getting-started.md
@@ -10,7 +10,7 @@ This guide will help you install {{ site.spout_html }} and teach you how to use
 
 ## Requirements
 
-* PHP version 7.1 or higher
+* PHP version 7.2 or higher
 * PHP extension `ext-zip` enabled
 * PHP extension `ext-xmlreader` enabled
 
diff --git a/docs/_pages/guides/4-symfony-stream-content-large-spreadsheet.md b/docs/_pages/guides/4-symfony-stream-content-large-spreadsheet.md
index fb203ae..165a4b3 100644
--- a/docs/_pages/guides/4-symfony-stream-content-large-spreadsheet.md
+++ b/docs/_pages/guides/4-symfony-stream-content-large-spreadsheet.md
@@ -94,7 +94,7 @@ class MyStreamController extends Controller
 
                     $i++;
                     // Flushing the buffer every N rows to stream echo'ed content.
-                    if ($i % FLUSH_THRESHOLD === 0) {
+                    if ($i % self::FLUSH_THRESHOLD === 0) {
                         flush();
                     }
                 }
diff --git a/phpunit.xml b/phpunit.xml
index 4c56189..4e410e2 100644
--- a/phpunit.xml
+++ b/phpunit.xml
@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <phpunit xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
-        xsi:noNamespaceSchemaLocation="https://schema.phpunit.de/7.5/phpunit.xsd"
+        xsi:noNamespaceSchemaLocation="https://schema.phpunit.de/8.5/phpunit.xsd"
         bootstrap="tests/bootstrap.php"
         colors="true"
         convertErrorsToExceptions="false"
diff --git a/src/Spout/Common/Entity/Style/Style.php b/src/Spout/Common/Entity/Style/Style.php
index 7e989a4..2bacc7a 100644
--- a/src/Spout/Common/Entity/Style/Style.php
+++ b/src/Spout/Common/Entity/Style/Style.php
@@ -84,6 +84,12 @@ class Style
     /** @var bool */
     private $hasSetFormat = false;
 
+    /** @var bool */
+    private $isRegistered = false;
+
+    /** @var bool */
+    private $isEmpty = true;
+
     /**
      * @return int|null
      */
@@ -119,6 +125,7 @@ class Style
     {
         $this->shouldApplyBorder = true;
         $this->border = $border;
+        $this->isEmpty = false;
 
         return $this;
     }
@@ -147,6 +154,7 @@ class Style
         $this->fontBold = true;
         $this->hasSetFontBold = true;
         $this->shouldApplyFont = true;
+        $this->isEmpty = false;
 
         return $this;
     }
@@ -175,6 +183,7 @@ class Style
         $this->fontItalic = true;
         $this->hasSetFontItalic = true;
         $this->shouldApplyFont = true;
+        $this->isEmpty = false;
 
         return $this;
     }
@@ -203,6 +212,7 @@ class Style
         $this->fontUnderline = true;
         $this->hasSetFontUnderline = true;
         $this->shouldApplyFont = true;
+        $this->isEmpty = false;
 
         return $this;
     }
@@ -231,6 +241,7 @@ class Style
         $this->fontStrikethrough = true;
         $this->hasSetFontStrikethrough = true;
         $this->shouldApplyFont = true;
+        $this->isEmpty = false;
 
         return $this;
     }
@@ -260,6 +271,7 @@ class Style
         $this->fontSize = $fontSize;
         $this->hasSetFontSize = true;
         $this->shouldApplyFont = true;
+        $this->isEmpty = false;
 
         return $this;
     }
@@ -291,6 +303,7 @@ class Style
         $this->fontColor = $fontColor;
         $this->hasSetFontColor = true;
         $this->shouldApplyFont = true;
+        $this->isEmpty = false;
 
         return $this;
     }
@@ -320,6 +333,7 @@ class Style
         $this->fontName = $fontName;
         $this->hasSetFontName = true;
         $this->shouldApplyFont = true;
+        $this->isEmpty = false;
 
         return $this;
     }
@@ -350,6 +364,7 @@ class Style
         $this->cellAlignment = $cellAlignment;
         $this->hasSetCellAlignment = true;
         $this->shouldApplyCellAlignment = true;
+        $this->isEmpty = false;
 
         return $this;
     }
@@ -386,6 +401,7 @@ class Style
     {
         $this->shouldWrapText = $shouldWrap;
         $this->hasSetWrapText = true;
+        $this->isEmpty = false;
 
         return $this;
     }
@@ -415,6 +431,7 @@ class Style
     {
         $this->hasSetBackgroundColor = true;
         $this->backgroundColor = $color;
+        $this->isEmpty = false;
 
         return $this;
     }
@@ -444,6 +461,7 @@ class Style
     {
         $this->hasSetFormat = true;
         $this->format = $format;
+        $this->isEmpty = false;
 
         return $this;
     }
@@ -463,4 +481,29 @@ class Style
     {
         return $this->hasSetFormat;
     }
+
+    /**
+     * @return bool
+     */
+    public function isRegistered() : bool
+    {
+        return $this->isRegistered;
+    }
+
+    public function markAsRegistered(?int $id) : void
+    {
+        $this->setId($id);
+        $this->isRegistered = true;
+    }
+
+    public function unmarkAsRegistered() : void
+    {
+        $this->setId(0);
+        $this->isRegistered = false;
+    }
+
+    public function isEmpty() : bool
+    {
+        return $this->isEmpty;
+    }
 }
diff --git a/src/Spout/Writer/Common/Manager/RegisteredStyle.php b/src/Spout/Writer/Common/Manager/RegisteredStyle.php
new file mode 100644
index 0000000..734c2b6
--- /dev/null
+++ b/src/Spout/Writer/Common/Manager/RegisteredStyle.php
@@ -0,0 +1,38 @@
+<?php
+
+namespace Box\Spout\Writer\Common\Manager;
+
+use Box\Spout\Common\Entity\Style\Style;
+
+/**
+ * Class RegisteredStyle
+ * Allow to know if this style must replace actual row style.
+ */
+class RegisteredStyle
+{
+    /**
+     * @var Style
+     */
+    private $style;
+
+    /**
+     * @var bool
+     */
+    private $isMatchingRowStyle;
+
+    public function __construct(Style $style, bool $isMatchingRowStyle)
+    {
+        $this->style = $style;
+        $this->isMatchingRowStyle = $isMatchingRowStyle;
+    }
+
+    public function getStyle() : Style
+    {
+        return $this->style;
+    }
+
+    public function isMatchingRowStyle() : bool
+    {
+        return $this->isMatchingRowStyle;
+    }
+}
diff --git a/src/Spout/Writer/Common/Manager/Style/PossiblyUpdatedStyle.php b/src/Spout/Writer/Common/Manager/Style/PossiblyUpdatedStyle.php
new file mode 100644
index 0000000..6ccaa29
--- /dev/null
+++ b/src/Spout/Writer/Common/Manager/Style/PossiblyUpdatedStyle.php
@@ -0,0 +1,32 @@
+<?php
+
+namespace Box\Spout\Writer\Common\Manager\Style;
+
+use Box\Spout\Common\Entity\Style\Style;
+
+/**
+ * Class PossiblyUpdatedStyle
+ * Indicates if style is updated.
+ * It allow to know if style registration must be done.
+ */
+class PossiblyUpdatedStyle
+{
+    private $style;
+    private $isUpdated;
+
+    public function __construct(Style $style, bool $isUpdated)
+    {
+        $this->style = $style;
+        $this->isUpdated = $isUpdated;
+    }
+
+    public function getStyle() : Style
+    {
+        return $this->style;
+    }
+
+    public function isUpdated() : bool
+    {
+        return $this->isUpdated;
+    }
+}
diff --git a/src/Spout/Writer/Common/Manager/Style/StyleManager.php b/src/Spout/Writer/Common/Manager/Style/StyleManager.php
index 77eec73..e2b5ebd 100644
--- a/src/Spout/Writer/Common/Manager/Style/StyleManager.php
+++ b/src/Spout/Writer/Common/Manager/Style/StyleManager.php
@@ -50,13 +50,11 @@ class StyleManager implements StyleManagerInterface
      * Typically, set "wrap text" if a cell contains a new line.
      *
      * @param Cell $cell
-     * @return Style
+     * @return PossiblyUpdatedStyle The eventually updated style
      */
-    public function applyExtraStylesIfNeeded(Cell $cell)
+    public function applyExtraStylesIfNeeded(Cell $cell) : PossiblyUpdatedStyle
     {
-        $updatedStyle = $this->applyWrapTextIfCellContainsNewLine($cell);
-
-        return $updatedStyle;
+        return $this->applyWrapTextIfCellContainsNewLine($cell);
     }
 
     /**
@@ -69,21 +67,19 @@ class StyleManager implements StyleManagerInterface
      *        on the Windows version of Excel...
      *
      * @param Cell $cell The cell the style should be applied to
-     * @return \Box\Spout\Common\Entity\Style\Style The eventually updated style
+     * @return PossiblyUpdatedStyle The eventually updated style
      */
-    protected function applyWrapTextIfCellContainsNewLine(Cell $cell)
+    protected function applyWrapTextIfCellContainsNewLine(Cell $cell) : PossiblyUpdatedStyle
     {
         $cellStyle = $cell->getStyle();
 
         // if the "wrap text" option is already set, no-op
-        if ($cellStyle->hasSetWrapText()) {
-            return $cellStyle;
-        }
-
-        if ($cell->isString() && \strpos($cell->getValue(), "\n") !== false) {
+        if (!$cellStyle->hasSetWrapText() && $cell->isString() && \strpos($cell->getValue(), "\n") !== false) {
             $cellStyle->setShouldWrapText();
+
+            return new PossiblyUpdatedStyle($cellStyle, true);
         }
 
-        return $cellStyle;
+        return new PossiblyUpdatedStyle($cellStyle, false);
     }
 }
diff --git a/src/Spout/Writer/Common/Manager/Style/StyleManagerInterface.php b/src/Spout/Writer/Common/Manager/Style/StyleManagerInterface.php
index 312588e..6b320b1 100644
--- a/src/Spout/Writer/Common/Manager/Style/StyleManagerInterface.php
+++ b/src/Spout/Writer/Common/Manager/Style/StyleManagerInterface.php
@@ -24,7 +24,7 @@ interface StyleManagerInterface
      * Typically, set "wrap text" if a cell contains a new line.
      *
      * @param Cell $cell
-     * @return Style The updated style
+     * @return PossiblyUpdatedStyle The eventually updated style
      */
-    public function applyExtraStylesIfNeeded(Cell $cell);
+    public function applyExtraStylesIfNeeded(Cell $cell) : PossiblyUpdatedStyle;
 }
diff --git a/src/Spout/Writer/Common/Manager/Style/StyleRegistry.php b/src/Spout/Writer/Common/Manager/Style/StyleRegistry.php
index d9e315f..6b439a7 100644
--- a/src/Spout/Writer/Common/Manager/Style/StyleRegistry.php
+++ b/src/Spout/Writer/Common/Manager/Style/StyleRegistry.php
@@ -36,9 +36,9 @@ class StyleRegistry
     {
         $serializedStyle = $this->serialize($style);
 
-        if (!$this->hasStyleAlreadyBeenRegistered($style)) {
+        if (!$this->hasSerializedStyleAlreadyBeenRegistered($serializedStyle)) {
             $nextStyleId = \count($this->serializedStyleToStyleIdMappingTable);
-            $style->setId($nextStyleId);
+            $style->markAsRegistered($nextStyleId);
 
             $this->serializedStyleToStyleIdMappingTable[$serializedStyle] = $nextStyleId;
             $this->styleIdToStyleMappingTable[$nextStyleId] = $style;
@@ -48,15 +48,13 @@ class StyleRegistry
     }
 
     /**
-     * Returns whether the given style has already been registered.
+     * Returns whether the serialized style has already been registered.
      *
-     * @param Style $style
+     * @param string $serializedStyle The serialized style
      * @return bool
      */
-    protected function hasStyleAlreadyBeenRegistered(Style $style)
+    protected function hasSerializedStyleAlreadyBeenRegistered(string $serializedStyle)
     {
-        $serializedStyle = $this->serialize($style);
-
         // Using isset here because it is way faster than array_key_exists...
         return isset($this->serializedStyleToStyleIdMappingTable[$serializedStyle]);
     }
@@ -101,13 +99,13 @@ class StyleRegistry
      */
     public function serialize(Style $style)
     {
-        // In order to be able to properly compare style, set static ID value
+        // In order to be able to properly compare style, set static ID value and reset registration
         $currentId = $style->getId();
-        $style->setId(0);
+        $style->unmarkAsRegistered();
 
         $serializedStyle = \serialize($style);
 
-        $style->setId($currentId);
+        $style->markAsRegistered($currentId);
 
         return $serializedStyle;
     }
diff --git a/src/Spout/Writer/ODS/Manager/Style/StyleRegistry.php b/src/Spout/Writer/ODS/Manager/Style/StyleRegistry.php
index 6c580d4..42484f2 100644
--- a/src/Spout/Writer/ODS/Manager/Style/StyleRegistry.php
+++ b/src/Spout/Writer/ODS/Manager/Style/StyleRegistry.php
@@ -22,6 +22,10 @@ class StyleRegistry extends \Box\Spout\Writer\Common\Manager\Style\StyleRegistry
      */
     public function registerStyle(Style $style)
     {
+        if ($style->isRegistered()) {
+            return $style;
+        }
+
         $registeredStyle = parent::registerStyle($style);
         $this->usedFontsSet[$style->getFontName()] = true;
 
diff --git a/src/Spout/Writer/ODS/Manager/WorksheetManager.php b/src/Spout/Writer/ODS/Manager/WorksheetManager.php
index 38cd6c5..544945b 100644
--- a/src/Spout/Writer/ODS/Manager/WorksheetManager.php
+++ b/src/Spout/Writer/ODS/Manager/WorksheetManager.php
@@ -10,6 +10,7 @@ use Box\Spout\Common\Exception\IOException;
 use Box\Spout\Common\Helper\Escaper\ODS as ODSEscaper;
 use Box\Spout\Common\Helper\StringHelper;
 use Box\Spout\Writer\Common\Entity\Worksheet;
+use Box\Spout\Writer\Common\Manager\RegisteredStyle;
 use Box\Spout\Writer\Common\Manager\Style\StyleMerger;
 use Box\Spout\Writer\Common\Manager\WorksheetManagerInterface;
 use Box\Spout\Writer\ODS\Manager\Style\StyleManager;
@@ -104,8 +105,8 @@ class WorksheetManager implements WorksheetManagerInterface
      *
      * @param Worksheet $worksheet The worksheet to add the row to
      * @param Row $row The row to be added
-     * @throws IOException If the data cannot be written
      * @throws InvalidArgumentException If a cell value's type is not supported
+     * @throws IOException If the data cannot be written
      * @return void
      */
     public function addRow(Worksheet $worksheet, Row $row)
@@ -125,7 +126,13 @@ class WorksheetManager implements WorksheetManagerInterface
             $nextCell = isset($cells[$nextCellIndex]) ? $cells[$nextCellIndex] : null;
 
             if ($nextCell === null || $cell->getValue() !== $nextCell->getValue()) {
-                $data .= $this->applyStyleAndGetCellXML($cell, $rowStyle, $currentCellIndex, $nextCellIndex);
+                $registeredStyle = $this->applyStyleAndRegister($cell, $rowStyle);
+                $cellStyle = $registeredStyle->getStyle();
+                if ($registeredStyle->isMatchingRowStyle()) {
+                    $rowStyle = $cellStyle; // Replace actual rowStyle (possibly with null id) by registered style (with id)
+                }
+
+                $data .= $this->getCellXMLWithStyle($cell, $cellStyle, $currentCellIndex, $nextCellIndex);
                 $currentCellIndex = $nextCellIndex;
             }
 
@@ -146,24 +153,46 @@ class WorksheetManager implements WorksheetManagerInterface
 
     /**
      * Applies styles to the given style, merging the cell's style with its row's style
-     * Then builds and returns xml for the cell.
      *
      * @param Cell $cell
      * @param Style $rowStyle
-     * @param int $currentCellIndex
-     * @param int $nextCellIndex
      * @throws InvalidArgumentException If a cell value's type is not supported
-     * @return string
+     * @return RegisteredStyle
      */
-    private function applyStyleAndGetCellXML(Cell $cell, Style $rowStyle, $currentCellIndex, $nextCellIndex)
+    private function applyStyleAndRegister(Cell $cell, Style $rowStyle) : RegisteredStyle
     {
-        // Apply row and extra styles
-        $mergedCellAndRowStyle = $this->styleMerger->merge($cell->getStyle(), $rowStyle);
-        $cell->setStyle($mergedCellAndRowStyle);
-        $newCellStyle = $this->styleManager->applyExtraStylesIfNeeded($cell);
+        $isMatchingRowStyle = false;
+        if ($cell->getStyle()->isEmpty()) {
+            $cell->setStyle($rowStyle);
 
-        $registeredStyle = $this->styleManager->registerStyle($newCellStyle);
-        $styleIndex = $registeredStyle->getId() + 1; // 1-based
+            $possiblyUpdatedStyle = $this->styleManager->applyExtraStylesIfNeeded($cell);
+
+            if ($possiblyUpdatedStyle->isUpdated()) {
+                $registeredStyle = $this->styleManager->registerStyle($possiblyUpdatedStyle->getStyle());
+            } else {
+                $registeredStyle = $this->styleManager->registerStyle($rowStyle);
+                $isMatchingRowStyle = true;
+            }
+        } else {
+            $mergedCellAndRowStyle = $this->styleMerger->merge($cell->getStyle(), $rowStyle);
+            $cell->setStyle($mergedCellAndRowStyle);
+
+            $possiblyUpdatedStyle = $this->styleManager->applyExtraStylesIfNeeded($cell);
+            if ($possiblyUpdatedStyle->isUpdated()) {
+                $newCellStyle = $possiblyUpdatedStyle->getStyle();
+            } else {
+                $newCellStyle = $mergedCellAndRowStyle;
+            }
+
+            $registeredStyle = $this->styleManager->registerStyle($newCellStyle);
+        }
+
+        return new RegisteredStyle($registeredStyle, $isMatchingRowStyle);
+    }
+
+    private function getCellXMLWithStyle(Cell $cell, Style $style, int $currentCellIndex, int $nextCellIndex) : string
+    {
+        $styleIndex = $style->getId() + 1; // 1-based
 
         $numTimesValueRepeated = ($nextCellIndex - $currentCellIndex);
 
@@ -197,7 +226,8 @@ class WorksheetManager implements WorksheetManagerInterface
 
             $data .= '</table:table-cell>';
         } elseif ($cell->isBoolean()) {
-            $data .= ' office:value-type="boolean" calcext:value-type="boolean" office:boolean-value="' . $cell->getValue() . '">';
+            $value = $cell->getValue() ? 'true' : 'false'; // boolean-value spec: http://docs.oasis-open.org/office/v1.2/os/OpenDocument-v1.2-os-part1.html#datatype-boolean
+            $data .= ' office:value-type="boolean" calcext:value-type="boolean" office:boolean-value="' . $value . '">';
             $data .= '<text:p>' . $cell->getValue() . '</text:p>';
             $data .= '</table:table-cell>';
         } elseif ($cell->isNumeric()) {
diff --git a/src/Spout/Writer/WriterAbstract.php b/src/Spout/Writer/WriterAbstract.php
index bbaa735..36a583f 100644
--- a/src/Spout/Writer/WriterAbstract.php
+++ b/src/Spout/Writer/WriterAbstract.php
@@ -123,9 +123,26 @@ abstract class WriterAbstract implements WriterInterface
         // @see https://github.com/box/spout/issues/241
         $this->globalFunctionsHelper->ob_end_clean();
 
-        // Set headers
+        /*
+         * Set headers
+         *
+         * For newer browsers such as Firefox, Chrome, Opera, Safari, etc., they all support and use `filename*`
+         * specified by the new standard, even if they do not automatically decode filename; it does not matter;
+         * and for older versions of Internet Explorer, they are not recognized `filename*`, will automatically
+         * ignore it and use the old `filename` (the only minor flaw is that there must be an English suffix name).
+         * In this way, the multi-browser multi-language compatibility problem is perfectly solved, which does not
+         * require UA judgment and is more in line with the standard.
+         *
+         * @see https://github.com/box/spout/issues/745
+         * @see https://tools.ietf.org/html/rfc6266
+         * @see https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Content-Disposition
+         */
         $this->globalFunctionsHelper->header('Content-Type: ' . static::$headerContentType);
-        $this->globalFunctionsHelper->header('Content-Disposition: attachment; filename="' . $this->outputFilePath . '"');
+        $this->globalFunctionsHelper->header(
+            'Content-Disposition: attachment; ' .
+            'filename="' . rawurldecode($this->outputFilePath) . '"; ' .
+            'filename*=UTF-8\'\'' . rawurldecode($this->outputFilePath)
+        );
 
         /*
          * When forcing the download of a file over SSL,IE8 and lower browsers fail
diff --git a/src/Spout/Writer/XLSX/Manager/Style/StyleRegistry.php b/src/Spout/Writer/XLSX/Manager/Style/StyleRegistry.php
index ace607c..14eb986 100644
--- a/src/Spout/Writer/XLSX/Manager/Style/StyleRegistry.php
+++ b/src/Spout/Writer/XLSX/Manager/Style/StyleRegistry.php
@@ -119,6 +119,10 @@ class StyleRegistry extends \Box\Spout\Writer\Common\Manager\Style\StyleRegistry
      */
     public function registerStyle(Style $style)
     {
+        if ($style->isRegistered()) {
+            return $style;
+        }
+
         $registeredStyle = parent::registerStyle($style);
         $this->registerFill($registeredStyle);
         $this->registerFormat($registeredStyle);
diff --git a/src/Spout/Writer/XLSX/Manager/WorksheetManager.php b/src/Spout/Writer/XLSX/Manager/WorksheetManager.php
index 7c33e06..51ded12 100644
--- a/src/Spout/Writer/XLSX/Manager/WorksheetManager.php
+++ b/src/Spout/Writer/XLSX/Manager/WorksheetManager.php
@@ -14,6 +14,7 @@ use Box\Spout\Writer\Common\Creator\InternalEntityFactory;
 use Box\Spout\Writer\Common\Entity\Options;
 use Box\Spout\Writer\Common\Entity\Worksheet;
 use Box\Spout\Writer\Common\Helper\CellHelper;
+use Box\Spout\Writer\Common\Manager\RegisteredStyle;
 use Box\Spout\Writer\Common\Manager\ManagesCellSize;
 use Box\Spout\Writer\Common\Manager\RowManager;
 use Box\Spout\Writer\Common\Manager\Style\StyleMerger;
@@ -185,7 +186,12 @@ EOD;
         $rowXML = "<row r=\"{$rowIndexOneBased}\" spans=\"1:{$numCells}\" customHeight=\"{$hasCustomHeight}\">";
 
         foreach ($row->getCells() as $columnIndexZeroBased => $cell) {
-            $rowXML .= $this->applyStyleAndGetCellXML($cell, $rowStyle, $rowIndexOneBased, $columnIndexZeroBased);
+            $registeredStyle = $this->applyStyleAndRegister($cell, $rowStyle);
+            $cellStyle = $registeredStyle->getStyle();
+            if ($registeredStyle->isMatchingRowStyle()) {
+                $rowStyle = $cellStyle; // Replace actual rowStyle (possibly with null id) by registered style (with id)
+            }
+            $rowXML .= $this->getCellXML($rowIndexOneBased, $columnIndexZeroBased, $cell, $cellStyle->getId());
         }
 
         $rowXML .= '</row>';
@@ -198,26 +204,43 @@ EOD;
 
     /**
      * Applies styles to the given style, merging the cell's style with its row's style
-     * Then builds and returns xml for the cell.
      *
      * @param Cell $cell
      * @param Style $rowStyle
-     * @param int $rowIndexOneBased
-     * @param int $columnIndexZeroBased
      *
      * @throws InvalidArgumentException If the given value cannot be processed
-     * @return string
+     * @return RegisteredStyle
      */
-    private function applyStyleAndGetCellXML(Cell $cell, Style $rowStyle, $rowIndexOneBased, $columnIndexZeroBased)
+    private function applyStyleAndRegister(Cell $cell, Style $rowStyle) : RegisteredStyle
     {
-        // Apply row and extra styles
-        $mergedCellAndRowStyle = $this->styleMerger->merge($cell->getStyle(), $rowStyle);
-        $cell->setStyle($mergedCellAndRowStyle);
-        $newCellStyle = $this->styleManager->applyExtraStylesIfNeeded($cell);
+        $isMatchingRowStyle = false;
+        if ($cell->getStyle()->isEmpty()) {
+            $cell->setStyle($rowStyle);
 
-        $registeredStyle = $this->styleManager->registerStyle($newCellStyle);
+            $possiblyUpdatedStyle = $this->styleManager->applyExtraStylesIfNeeded($cell);
 
-        return $this->getCellXML($rowIndexOneBased, $columnIndexZeroBased, $cell, $registeredStyle->getId());
+            if ($possiblyUpdatedStyle->isUpdated()) {
+                $registeredStyle = $this->styleManager->registerStyle($possiblyUpdatedStyle->getStyle());
+            } else {
+                $registeredStyle = $this->styleManager->registerStyle($rowStyle);
+                $isMatchingRowStyle = true;
+            }
+        } else {
+            $mergedCellAndRowStyle = $this->styleMerger->merge($cell->getStyle(), $rowStyle);
+            $cell->setStyle($mergedCellAndRowStyle);
+
+            $possiblyUpdatedStyle = $this->styleManager->applyExtraStylesIfNeeded($cell);
+
+            if ($possiblyUpdatedStyle->isUpdated()) {
+                $newCellStyle = $possiblyUpdatedStyle->getStyle();
+            } else {
+                $newCellStyle = $mergedCellAndRowStyle;
+            }
+
+            $registeredStyle = $this->styleManager->registerStyle($newCellStyle);
+        }
+
+        return new RegisteredStyle($registeredStyle, $isMatchingRowStyle);
     }
 
     /**
diff --git a/tests/Spout/Common/Entity/RowTest.php b/tests/Spout/Common/Entity/RowTest.php
index 095025c..9aa12f6 100644
--- a/tests/Spout/Common/Entity/RowTest.php
+++ b/tests/Spout/Common/Entity/RowTest.php
@@ -122,6 +122,6 @@ class RowTest extends \PHPUnit\Framework\TestCase
             ->setStyle($this->getStyleMock())
             ->setCells([]);
 
-        $this->assertInternalType('object', $row);
+        $this->assertInstanceOf(Row::class, $row);
     }
 }
diff --git a/tests/Spout/Common/Helper/FileSystemHelperTest.php b/tests/Spout/Common/Helper/FileSystemHelperTest.php
index f99ab30..7eb0183 100644
--- a/tests/Spout/Common/Helper/FileSystemHelperTest.php
+++ b/tests/Spout/Common/Helper/FileSystemHelperTest.php
@@ -16,7 +16,7 @@ class FileSystemHelperTest extends TestCase
     /**
      * @return void
      */
-    public function setUp()
+    public function setUp() : void
     {
         $baseFolder = \sys_get_temp_dir();
         $this->fileSystemHelper = new FileSystemHelper($baseFolder);
diff --git a/tests/Spout/Common/Manager/OptionsManagerTest.php b/tests/Spout/Common/Manager/OptionsManagerTest.php
index e2f0c5c..d5fe5d8 100644
--- a/tests/Spout/Common/Manager/OptionsManagerTest.php
+++ b/tests/Spout/Common/Manager/OptionsManagerTest.php
@@ -14,7 +14,7 @@ class OptionsManagerTest extends TestCase
      */
     protected $optionsManager;
 
-    protected function setUp()
+    protected function setUp() : void
     {
         $this->optionsManager = new class() extends OptionsManagerAbstract {
             protected function getSupportedOptions()
diff --git a/tests/Spout/Reader/ODS/ReaderTest.php b/tests/Spout/Reader/ODS/ReaderTest.php
index ce56e4b..cd30ae5 100644
--- a/tests/Spout/Reader/ODS/ReaderTest.php
+++ b/tests/Spout/Reader/ODS/ReaderTest.php
@@ -295,6 +295,10 @@ class ReaderTest extends TestCase
      */
     public function testReadShouldBeProtectedAgainstBillionLaughsAttack()
     {
+        if (function_exists('xdebug_code_coverage_started') && xdebug_code_coverage_started()) {
+            $this->markTestSkipped('test not compatible with code coverage');
+        }
+
         $startTime = microtime(true);
         $fileName = 'attack_billion_laughs.ods';
 
@@ -318,6 +322,10 @@ class ReaderTest extends TestCase
      */
     public function testReadShouldBeProtectedAgainstQuadraticBlowupAttack()
     {
+        if (function_exists('xdebug_code_coverage_started') && xdebug_code_coverage_started()) {
+            $this->markTestSkipped('test not compatible with code coverage');
+        }
+
         $startTime = microtime(true);
 
         $fileName = 'attack_quadratic_blowup.ods';
diff --git a/tests/Spout/Reader/XLSX/Manager/SharedStringsManagerTest.php b/tests/Spout/Reader/XLSX/Manager/SharedStringsManagerTest.php
index 2f85f34..f344b35 100644
--- a/tests/Spout/Reader/XLSX/Manager/SharedStringsManagerTest.php
+++ b/tests/Spout/Reader/XLSX/Manager/SharedStringsManagerTest.php
@@ -25,7 +25,7 @@ class SharedStringsManagerTest extends TestCase
     /**
      * @return void
      */
-    public function setUp()
+    public function setUp() : void
     {
         $this->sharedStringsManager = null;
     }
@@ -33,7 +33,7 @@ class SharedStringsManagerTest extends TestCase
     /**
      * @return void
      */
-    public function tearDown()
+    public function tearDown() : void
     {
         if ($this->sharedStringsManager !== null) {
             $this->sharedStringsManager->cleanup();
diff --git a/tests/Spout/Reader/XLSX/ReaderTest.php b/tests/Spout/Reader/XLSX/ReaderTest.php
index 51a7b0e..7d30f97 100644
--- a/tests/Spout/Reader/XLSX/ReaderTest.php
+++ b/tests/Spout/Reader/XLSX/ReaderTest.php
@@ -539,6 +539,10 @@ class ReaderTest extends TestCase
      */
     public function testReadShouldBeProtectedAgainstQuadraticBlowupAttack()
     {
+        if (function_exists('xdebug_code_coverage_started') && xdebug_code_coverage_started()) {
+            $this->markTestSkipped('test not compatible with code coverage');
+        }
+
         $startTime = microtime(true);
 
         $this->getAllRowsForFile('attack_quadratic_blowup.xlsx');
diff --git a/tests/Spout/Writer/CSV/WriterPerfTest.php b/tests/Spout/Writer/CSV/WriterPerfTest.php
index 4172bf5..cbfcae0 100644
--- a/tests/Spout/Writer/CSV/WriterPerfTest.php
+++ b/tests/Spout/Writer/CSV/WriterPerfTest.php
@@ -61,7 +61,7 @@ class WriterPerfTest extends TestCase
      */
     private function getNumWrittenRows($resourcePath)
     {
-        $lineCountResult = `wc -l $resourcePath`;
+        $lineCountResult = shell_exec("wc -l $resourcePath");
 
         return (int) $lineCountResult;
     }
diff --git a/tests/Spout/Writer/CSV/WriterTest.php b/tests/Spout/Writer/CSV/WriterTest.php
index 0b3b238..deb3f22 100644
--- a/tests/Spout/Writer/CSV/WriterTest.php
+++ b/tests/Spout/Writer/CSV/WriterTest.php
@@ -101,7 +101,7 @@ class WriterTest extends TestCase
         ]);
         $writtenContent = $this->writeToCsvFileAndReturnWrittenContent($allRows, 'csv_with_utf8_bom.csv');
 
-        $this->assertContains(EncodingHelper::BOM_UTF8, $writtenContent, 'The CSV file should contain a UTF-8 BOM');
+        $this->assertStringStartsWith(EncodingHelper::BOM_UTF8, $writtenContent, 'The CSV file should contain a UTF-8 BOM');
     }
 
     /**
@@ -114,7 +114,7 @@ class WriterTest extends TestCase
         ]);
         $writtenContent = $this->writeToCsvFileAndReturnWrittenContent($allRows, 'csv_no_bom.csv', ',', '"', false);
 
-        $this->assertNotContains(EncodingHelper::BOM_UTF8, $writtenContent, 'The CSV file should not contain a UTF-8 BOM');
+        $this->assertStringNotContainsString(EncodingHelper::BOM_UTF8, $writtenContent, 'The CSV file should not contain a UTF-8 BOM');
     }
 
     /**
diff --git a/tests/Spout/Writer/Common/Entity/SheetTest.php b/tests/Spout/Writer/Common/Entity/SheetTest.php
index cb19d6f..e0cf8ee 100644
--- a/tests/Spout/Writer/Common/Entity/SheetTest.php
+++ b/tests/Spout/Writer/Common/Entity/SheetTest.php
@@ -18,7 +18,7 @@ class SheetTest extends TestCase
     /**
      * @return void
      */
-    public function setUp()
+    public function setUp() : void
     {
         $this->sheetManager = new SheetManager(new StringHelper());
     }
diff --git a/tests/Spout/Writer/Common/Manager/Style/StyleManagerTest.php b/tests/Spout/Writer/Common/Manager/Style/StyleManagerTest.php
index 82292bb..5bbbe5c 100644
--- a/tests/Spout/Writer/Common/Manager/Style/StyleManagerTest.php
+++ b/tests/Spout/Writer/Common/Manager/Style/StyleManagerTest.php
@@ -14,7 +14,7 @@ class StyleManagerTest extends TestCase
     /**
      * @return StyleManager
      */
-    private function getStyleManager()
+    private function getStyleManager() : StyleManager
     {
         $style = (new StyleBuilder())->build();
         $styleRegistry = new StyleRegistry($style);
@@ -22,31 +22,37 @@ class StyleManagerTest extends TestCase
         return new StyleManager($styleRegistry);
     }
 
-    /**
-     * @return void
-     */
-    public function testApplyExtraStylesIfNeededShouldApplyWrapTextIfCellContainsNewLine()
+    public function testApplyExtraStylesIfNeededShouldApplyWrapTextIfCellContainsNewLine() : void
     {
         $style = (new StyleBuilder())->build();
         $this->assertFalse($style->shouldWrapText());
 
         $styleManager = $this->getStyleManager();
-        $updatedStyle = $styleManager->applyExtraStylesIfNeeded(new Cell("multi\nlines", $style));
+        $possiblyUpdatedStyle = $styleManager->applyExtraStylesIfNeeded(new Cell("multi\nlines", $style));
 
-        $this->assertTrue($updatedStyle->shouldWrapText());
+        $this->assertTrue($possiblyUpdatedStyle->isUpdated());
+        $this->assertTrue($possiblyUpdatedStyle->getStyle()->shouldWrapText());
     }
 
-    /**
-     * @return void
-     */
-    public function testApplyExtraStylesIfNeededShouldDoNothingIfWrapTextAlreadyApplied()
+    public function testApplyExtraStylesIfNeededShouldReturnNullIfWrapTextNotNeeded() : void
+    {
+        $style = (new StyleBuilder())->build();
+        $this->assertFalse($style->shouldWrapText());
+
+        $styleManager = $this->getStyleManager();
+        $possiblyUpdatedStyle = $styleManager->applyExtraStylesIfNeeded(new Cell('oneline', $style));
+
+        $this->assertFalse($possiblyUpdatedStyle->isUpdated());
+    }
+
+    public function testApplyExtraStylesIfNeededShouldReturnNullIfWrapTextAlreadyApplied() : void
     {
         $style = (new StyleBuilder())->setShouldWrapText()->build();
         $this->assertTrue($style->shouldWrapText());
 
         $styleManager = $this->getStyleManager();
-        $updatedStyle = $styleManager->applyExtraStylesIfNeeded(new Cell("multi\nlines", $style));
+        $possiblyUpdatedStyle = $styleManager->applyExtraStylesIfNeeded(new Cell("multi\nlines", $style));
 
-        $this->assertTrue($updatedStyle->shouldWrapText());
+        $this->assertFalse($possiblyUpdatedStyle->isUpdated());
     }
 }
diff --git a/tests/Spout/Writer/Common/Manager/Style/StyleMergerTest.php b/tests/Spout/Writer/Common/Manager/Style/StyleMergerTest.php
index 46820c0..b7c1607 100644
--- a/tests/Spout/Writer/Common/Manager/Style/StyleMergerTest.php
+++ b/tests/Spout/Writer/Common/Manager/Style/StyleMergerTest.php
@@ -18,7 +18,7 @@ class StyleMergerTest extends TestCase
     /**
      * @return void
      */
-    public function setUp()
+    public function setUp() : void
     {
         $this->styleMerger = new StyleMerger();
     }
diff --git a/tests/Spout/Writer/Common/Manager/Style/StyleRegistryTest.php b/tests/Spout/Writer/Common/Manager/Style/StyleRegistryTest.php
index 41cc571..ac78c9e 100644
--- a/tests/Spout/Writer/Common/Manager/Style/StyleRegistryTest.php
+++ b/tests/Spout/Writer/Common/Manager/Style/StyleRegistryTest.php
@@ -20,7 +20,7 @@ class StyleRegistryTest extends TestCase
     /**
      * @return void
      */
-    public function setUp()
+    public function setUp() : void
     {
         $this->defaultStyle = (new StyleBuilder())->build();
         $this->styleRegistry = new StyleRegistry($this->defaultStyle);
diff --git a/tests/Spout/Writer/ODS/SheetTest.php b/tests/Spout/Writer/ODS/SheetTest.php
index b5fec7b..f94f63c 100644
--- a/tests/Spout/Writer/ODS/SheetTest.php
+++ b/tests/Spout/Writer/ODS/SheetTest.php
@@ -90,7 +90,7 @@ class SheetTest extends TestCase
         $pathToContentFile = $resourcePath . '#content.xml';
         $xmlContents = file_get_contents('zip://' . $pathToContentFile);
 
-        $this->assertContains(' table:display="false"', $xmlContents, 'The sheet visibility should have been changed to "hidden"');
+        $this->assertStringContainsString(' table:display="false"', $xmlContents, 'The sheet visibility should have been changed to "hidden"');
     }
 
     public function testThrowsIfWorkbookIsNotInitialized()
@@ -285,6 +285,6 @@ class SheetTest extends TestCase
         $pathToWorkbookFile = $resourcePath . '#content.xml';
         $xmlContents = file_get_contents('zip://' . $pathToWorkbookFile);
 
-        $this->assertContains("table:name=\"$expectedName\"", $xmlContents, $message);
+        $this->assertStringContainsString("table:name=\"$expectedName\"", $xmlContents, $message);
     }
 }
diff --git a/tests/Spout/Writer/ODS/WriterPerfTest.php b/tests/Spout/Writer/ODS/WriterPerfTest.php
index 40c4ee0..5917b49 100644
--- a/tests/Spout/Writer/ODS/WriterPerfTest.php
+++ b/tests/Spout/Writer/ODS/WriterPerfTest.php
@@ -88,7 +88,7 @@ class WriterPerfTest extends TestCase
         copy($pathToContentXmlFile, $tmpFile);
 
         // Get the last 200 characters
-        $lastCharacters = `tail -c 200 $tmpFile`;
+        $lastCharacters = shell_exec("tail -c 200 $tmpFile");
 
         // remove the temporary file
         unlink($tmpFile);
diff --git a/tests/Spout/Writer/ODS/WriterTest.php b/tests/Spout/Writer/ODS/WriterTest.php
index b30a8f6..31dcccf 100644
--- a/tests/Spout/Writer/ODS/WriterTest.php
+++ b/tests/Spout/Writer/ODS/WriterTest.php
@@ -547,7 +547,7 @@ class WriterTest extends TestCase
         $pathToContentFile = $resourcePath . '#content.xml';
         $xmlContents = file_get_contents('zip://' . $pathToContentFile);
 
-        $this->assertContains($value, $xmlContents, $message);
+        $this->assertStringContainsString($value, $xmlContents, $message);
     }
 
     /**
@@ -562,7 +562,7 @@ class WriterTest extends TestCase
         $sheetXmlAsString = $this->getSheetXmlNodeAsString($fileName, $sheetIndex);
         $valueAsXmlString = "<text:p>$value</text:p>";
 
-        $this->assertContains($valueAsXmlString, $sheetXmlAsString, $message);
+        $this->assertStringContainsString($valueAsXmlString, $sheetXmlAsString, $message);
     }
 
     /**
@@ -577,7 +577,7 @@ class WriterTest extends TestCase
         $sheetXmlAsString = $this->getSheetXmlNodeAsString($fileName, $sheetIndex);
         $valueAsXmlString = "<text:p>$value</text:p>";
 
-        $this->assertNotContains($valueAsXmlString, $sheetXmlAsString, $message);
+        $this->assertStringNotContainsString($valueAsXmlString, $sheetXmlAsString, $message);
     }
 
     /**
diff --git a/tests/Spout/Writer/ODS/WriterWithStyleTest.php b/tests/Spout/Writer/ODS/WriterWithStyleTest.php
index dcdd364..75177da 100644
--- a/tests/Spout/Writer/ODS/WriterWithStyleTest.php
+++ b/tests/Spout/Writer/ODS/WriterWithStyleTest.php
@@ -30,7 +30,7 @@ class WriterWithStyleTest extends TestCase
     /**
      * @return void
      */
-    public function setUp()
+    public function setUp() : void
     {
         $this->defaultStyle = (new StyleBuilder())->build();
     }
diff --git a/tests/Spout/Writer/XLSX/SheetTest.php b/tests/Spout/Writer/XLSX/SheetTest.php
index f0caf1b..79033c2 100644
--- a/tests/Spout/Writer/XLSX/SheetTest.php
+++ b/tests/Spout/Writer/XLSX/SheetTest.php
@@ -90,7 +90,7 @@ class SheetTest extends TestCase
         $pathToWorkbookFile = $resourcePath . '#xl/workbook.xml';
         $xmlContents = file_get_contents('zip://' . $pathToWorkbookFile);
 
-        $this->assertContains(' state="hidden"', $xmlContents, 'The sheet visibility should have been changed to "hidden"');
+        $this->assertStringContainsString(' state="hidden"', $xmlContents, 'The sheet visibility should have been changed to "hidden"');
     }
 
     public function testThrowsIfWorkbookIsNotInitialized()
@@ -299,6 +299,6 @@ class SheetTest extends TestCase
         $pathToWorkbookFile = $resourcePath . '#xl/workbook.xml';
         $xmlContents = file_get_contents('zip://' . $pathToWorkbookFile);
 
-        $this->assertContains("<sheet name=\"$expectedName\"", $xmlContents, $message);
+        $this->assertStringContainsString("<sheet name=\"$expectedName\"", $xmlContents, $message);
     }
 }
diff --git a/tests/Spout/Writer/XLSX/WriterPerfTest.php b/tests/Spout/Writer/XLSX/WriterPerfTest.php
index f43381f..66ff337 100644
--- a/tests/Spout/Writer/XLSX/WriterPerfTest.php
+++ b/tests/Spout/Writer/XLSX/WriterPerfTest.php
@@ -135,7 +135,7 @@ class WriterPerfTest extends TestCase
         copy($filePath, $tmpFile);
 
         // Get the last 200 characters
-        $lastCharacters = `tail -c $numCharacters $tmpFile`;
+        $lastCharacters = shell_exec("tail -c $numCharacters $tmpFile");
 
         // remove the temporary file
         unlink($tmpFile);
diff --git a/tests/Spout/Writer/XLSX/WriterTest.php b/tests/Spout/Writer/XLSX/WriterTest.php
index 15cc4e4..9cc157a 100644
--- a/tests/Spout/Writer/XLSX/WriterTest.php
+++ b/tests/Spout/Writer/XLSX/WriterTest.php
@@ -608,7 +608,7 @@ class WriterTest extends TestCase
         $pathToSheetFile = $resourcePath . '#xl/worksheets/sheet' . $sheetIndex . '.xml';
         $xmlContents = file_get_contents('zip://' . $pathToSheetFile);
 
-        $this->assertContains((string) $inlineData, $xmlContents, $message);
+        $this->assertStringContainsString((string) $inlineData, $xmlContents, $message);
     }
 
     /**
@@ -624,7 +624,7 @@ class WriterTest extends TestCase
         $pathToSheetFile = $resourcePath . '#xl/worksheets/sheet' . $sheetIndex . '.xml';
         $xmlContents = file_get_contents('zip://' . $pathToSheetFile);
 
-        $this->assertNotContains((string) $inlineData, $xmlContents, $message);
+        $this->assertStringNotContainsString((string) $inlineData, $xmlContents, $message);
     }
 
     /**
@@ -639,6 +639,6 @@ class WriterTest extends TestCase
         $pathToSharedStringsFile = $resourcePath . '#xl/sharedStrings.xml';
         $xmlContents = file_get_contents('zip://' . $pathToSharedStringsFile);
 
-        $this->assertContains($sharedString, $xmlContents, $message);
+        $this->assertStringContainsString($sharedString, $xmlContents, $message);
     }
 }
diff --git a/tests/Spout/Writer/XLSX/WriterWithStyleTest.php b/tests/Spout/Writer/XLSX/WriterWithStyleTest.php
index da0aec2..2571df4 100644
--- a/tests/Spout/Writer/XLSX/WriterWithStyleTest.php
+++ b/tests/Spout/Writer/XLSX/WriterWithStyleTest.php
@@ -32,7 +32,7 @@ class WriterWithStyleTest extends TestCase
     /**
      * @return void
      */
-    public function setUp()
+    public function setUp() : void
     {
         $this->defaultStyle = (new StyleBuilder())->build();
     }