diff --git a/.travis.yml b/.travis.yml
index a1b9250..7df9d99 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -5,27 +5,29 @@ cache:
         - $HOME/.composer/cache
 
 php:
+    - '7.1'
     - '7.2'
     - '7.3'
     - '7.4'
+    - '8.0'
 
 jobs:
     fast_finish: true
     include:
-        - php: 7.4
-          env: COVERAGE=true
+        - php: 8.0
+          env: XDEBUG_MODE=coverage
           before_script:
             - curl -L https://codeclimate.com/downloads/test-reporter/test-reporter-latest-linux-amd64 > ./cc-test-reporter
             - chmod +x ./cc-test-reporter
           script:
-            - "phpunit --coverage-text --coverage-clover build/logs/clover.xml"
+            - "phpunit --coverage-text --coverage-clover clover.xml"
             - if [ "$TRAVIS_PULL_REQUEST" == "false" ]; then ./cc-test-reporter after-build -t clover --exit-code $TRAVIS_TEST_RESULT; fi
     allow_failures:
-        - env: COVERAGE=true
+        - env: XDEBUG_MODE=coverage
 
 before_script:
     # disable xdebug if not coverage
-    - if [[ $COVERAGE == "" ]]; then phpenv config-rm xdebug.ini; fi
+    - if [[ $XDEBUG_MODE == "" ]]; then phpenv config-rm xdebug.ini; fi
 
 install:
   - composer install --no-interaction --prefer-dist --no-ansi --no-progress --no-suggest
diff --git a/composer.json b/composer.json
index dbe2de4..885c13e 100644
--- a/composer.json
+++ b/composer.json
@@ -10,7 +10,7 @@
         }
     ],
     "require": {
-        "php" : "^7.1"
+        "php" : "^7.1 || ^8.0"
     },
     "autoload": {
         "psr-4": {
@@ -18,7 +18,7 @@
         }
     },
     "require-dev": {
-        "phpunit/phpunit": "^7.5.20|^8|^9",
+        "phpunit/phpunit": "^7.5.20 || ^8 || ^9",
         "phpstan/phpstan": "^0.12.5",
         "arxeiss/coding-standards": "^0.7.0"
     }
diff --git a/phpcs.xml b/phpcs.xml
index 17b6bce..df0250f 100644
--- a/phpcs.xml
+++ b/phpcs.xml
@@ -5,6 +5,8 @@
     <file>./src</file>
     <file>./tests</file>
 
+    <config name="php_version" value="70000"/>
+
     <arg name="basepath" value="."/> <!-- Strip file basepath from report -->
     <arg name="colors"/>
     <arg value="p"/><!-- Display progress in report -->
diff --git a/phpunit.xml b/phpunit.xml
index 463a98d..c572a64 100644
--- a/phpunit.xml
+++ b/phpunit.xml
@@ -1,20 +1,23 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<phpunit bootstrap="vendor/autoload.php"
-         colors="true"
-         convertErrorsToExceptions="true"
-         convertNoticesToExceptions="true"
-         convertWarningsToExceptions="true"
-         beStrictAboutOutputDuringTests="true"
-         failOnRisky="true"
-         testdox="true">
+<phpunit xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+        bootstrap="vendor/autoload.php"
+        colors="true"
+        convertErrorsToExceptions="true"
+        convertNoticesToExceptions="true"
+        convertWarningsToExceptions="true"
+        beStrictAboutOutputDuringTests="true"
+        failOnRisky="true"
+        testdox="true"
+        xsi:noNamespaceSchemaLocation="https://schema.phpunit.de/9.3/phpunit.xsd">
+
+    <coverage processUncoveredFiles="true">
+        <include>
+            <directory suffix=".php">./src</directory>
+        </include>
+    </coverage>
     <testsuites>
         <testsuite name="Units">
             <directory suffix="Test.php">./tests/Units</directory>
         </testsuite>
     </testsuites>
-    <filter>
-        <whitelist processUncoveredFilesFromWhitelist="true">
-            <directory suffix=".php">./src</directory>
-        </whitelist>
-    </filter>
 </phpunit>
diff --git a/src/Paginator.php b/src/Paginator.php
index 73cef0e..5e1d5a8 100644
--- a/src/Paginator.php
+++ b/src/Paginator.php
@@ -213,6 +213,9 @@ protected function applyBreakpointClasses(
 		}
 
 		[$leftDotsIndex, $middleIndex, $rightDotsIndex] = $this->getDotsIndex($paginator);
+		if ($middleIndex === null) {
+			$middleIndex = 0;
+		}
 
 		// There are no dots on the left side but breakpoint should hide some of the elements on the left side
 		if (!$leftDotsIndex && $this->currentPage > (int)\ceil($maxVisible / 2)) {
@@ -256,7 +259,7 @@ private function addButtonClasses(
 			$hideFromRight = $toHide;
 		} elseif ($leftDotsIndex && !$rightDotsIndex) {
 			$hideFromLeft = $toHide;
-		} elseif ($leftDotsIndex && $rightDotsIndex) {
+		} elseif ($leftDotsIndex) { // "&& $rightDotsIndex" has no effect on condition and is removed
 			// How many buttons around actual index should be visible
 			$middleVisibleOffset = (int)\ceil((\count($paginator->buttons) - $toHide - 5) / 2);
 			$hideFromLeft = $middleIndex - 2 - $middleVisibleOffset;
@@ -279,7 +282,7 @@ private function addButtonClasses(
 	}
 
 	/**
-	 * @return array<int>
+	 * @return array<?int>
 	 */
 	protected function getDotsIndex(Pages $paginator): array
 	{
@@ -308,16 +311,17 @@ static function ($button, $key) use ($middleIndex) {
 	/**
 	 * Search index in array by condition in callback
 	 *
-	 * @param  mixed[] $arr
-	 * @return mixed
+	 * @param mixed[] $arr
 	 */
-	private static function arrayCallbackSearch(array $arr, callable $searchCallback)
+	private static function arrayCallbackSearch(array $arr, callable $searchCallback): ?int
 	{
 		foreach ($arr as $key => $item) {
 			if (\call_user_func($searchCallback, $item, $key)) {
 				return $key;
 			}
 		}
+
+		return null;
 	}
 
 	/**