diff --git a/.travis.yml b/.travis.yml
index f761f2d..e6a836b 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,10 +1,8 @@
 language: php
 
 php:
-  - 5.5
-  - 5.6
-  - 7
-  - hhvm
+  - 7.1
+  - 7.2
 
 env:
   matrix:
@@ -16,10 +14,7 @@ before_script:
 
 script:
   - mkdir -p build/logs
-  - composer test
-
-  # phpcs only on latest PHP
-  - if [[ $TRAVIS_PHP_VERSION = '5.6' ]]; then composer phpcs; fi
+  - composer ci
 
 after_script:
   - php vendor/bin/coveralls -v
diff --git a/README.md b/README.md
index 8afb209..0f0eee1 100644
--- a/README.md
+++ b/README.md
@@ -17,7 +17,7 @@ Usage
 require_once 'vendor/autoload.php';
 
 $downloader = new FioApi\Downloader('TOKEN@todo');
-$transactionList = $downloader->downloadSince(new \DateTime('-1 week'));
+$transactionList = $downloader->downloadSince(new \DateTimeImmutable('-1 week'));
 
 foreach ($transactionList->getTransactions() as $transaction) {
     var_dump($transaction); //object with getters
@@ -27,7 +27,7 @@ foreach ($transactionList->getTransactions() as $transaction) {
 
 Requirements
 ------------
-Fio API PHP works with PHP 5.5, PHP 5.6 or PHP 7.
+Fio API PHP works with PHP 7 or higher.
 
 Submitting bugs and feature requests
 ------------------------------------
@@ -39,6 +39,21 @@ Martin Hujer - <mhujer@gmail.com> - <https://www.martinhujer.cz>
 
 Changelog
 ----------
+
+## 4.0.1 (2017-08-09)
+- [#12](https://github.com/mhujer/fio-api-php/pull/12) handle empty transaction list  (thx @soukicz!)
+
+## 4.0.0 (2017-08-04)
+- [#9](https://github.com/mhujer/fio-api-php/pull/9) minimal supported version is PHP 7.1
+- [#9](https://github.com/mhujer/fio-api-php/pull/9)`DateTime` replaced with `DateTimeImmutable` (or `DateTimeInterface`)
+- [#9](https://github.com/mhujer/fio-api-php/pull/9) strict types and primitive typehints are used everywhere
+
+## 3.0.0 (2016-11-24)
+- dropped support for PHP <7
+
+## 2.3.0 (2016-11-24)
+- [#7](https://github.com/mhujer/fio-api-php/pull/7): added official composer CA bundle support (@soukicz)
+
 ## 2.2.0 (2016-03-13)
 - [#2](https://github.com/mhujer/fio-api-php/pull/2): added [Kdyby/CurlCaBundle](https://github.com/Kdyby/CurlCaBundle)
  	as an optional dependency (@mhujer)
diff --git a/appveyor.yml b/appveyor.yml
index d664949..09cf7c8 100644
--- a/appveyor.yml
+++ b/appveyor.yml
@@ -17,13 +17,14 @@ init:
 install:
     - IF EXIST c:\php (SET PHP=0) ELSE (mkdir c:\php)
     - IF %PHP%==1 cd c:\php
-    - IF %PHP%==1 appveyor DownloadFile http://windows.php.net/downloads/releases/php-5.6.16-Win32-VC11-x86.zip
-    - IF %PHP%==1 7z x php-5.6.16-Win32-VC11-x86.zip -y >nul
+    - IF %PHP%==1 appveyor DownloadFile http://windows.php.net/downloads/releases/php-7.1.0-Win32-VC14-x86.zip
+    - IF %PHP%==1 7z x php-7.1.0-Win32-VC14-x86.zip -y >nul
     - IF %PHP%==1 copy /Y php.ini-development php.ini
     - IF %PHP%==1 echo max_execution_time=1200 >> php.ini
     - IF %PHP%==1 echo date.timezone="UTC" >> php.ini
     - IF %PHP%==1 echo extension_dir=ext >> php.ini
     - IF %PHP%==1 echo extension=php_curl.dll >> php.ini
+    - IF %PHP%==1 echo extension=php_mbstring.dll >> php.ini
     - IF %PHP%==1 echo extension=php_openssl.dll >> php.ini
     - IF %PHP%==1 del /Q *.zip
     - IF %PHP%==1 cd ..
diff --git a/composer.json b/composer.json
index 13a9abd..c0fd32c 100644
--- a/composer.json
+++ b/composer.json
@@ -18,17 +18,17 @@
     }
   ],
   "require": {
-    "php": ">=5.5",
+    "php": ">=7.1",
     "ext-curl": "*",
     "guzzlehttp/guzzle": "~6.1"
   },
   "require-dev": {
-    "phpunit/phpunit": "~4.7|~5.0",
-    "squizlabs/php_codesniffer": "~2.3",
+    "phpunit/phpunit": "~6.3",
+    "squizlabs/php_codesniffer": "~3.0",
     "satooshi/php-coveralls": "^1.0"
   },
   "suggest": {
-    "kdyby/curl-ca-bundle": "Provides regularly updated root certificates list"
+    "composer/ca-bundle": "Provides regularly updated root certificates list"
   },
   "autoload": {
     "psr-4": {
@@ -36,6 +36,10 @@
     }
   },
   "scripts": {
+    "ci": [
+      "@phpcs",
+      "@test"
+    ],
     "test": "phpunit",
     "phpcs": "phpcs --standard=PSR2 src && phpcs --standard=PSR2 tests"
   }
diff --git a/phpunit.xml.dist b/phpunit.xml.dist
index c29a516..700340d 100644
--- a/phpunit.xml.dist
+++ b/phpunit.xml.dist
@@ -2,14 +2,12 @@
 
 <phpunit
     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
-    xsi:noNamespaceSchemaLocation="http://schema.phpunit.de/4.6/phpunit.xsd"
+    xsi:noNamespaceSchemaLocation="http://schema.phpunit.de/6.3/phpunit.xsd"
     bootstrap="tests/bootstrap.php"
     colors="true"
-    beStrictAboutTestsThatDoNotTestAnything="true"
     beStrictAboutOutputDuringTests="true"
-    beStrictAboutTestSize="true"
     beStrictAboutTodoAnnotatedTests="true"
-    checkForUnintentionallyCoveredCode="true"
+    beStrictAboutChangesToGlobalState="true"
     >
     <testsuites>
         <testsuite name="FioApi Test Suite">
diff --git a/src/FioApi/Account.php b/src/FioApi/Account.php
index 17dbab3..5c8db35 100644
--- a/src/FioApi/Account.php
+++ b/src/FioApi/Account.php
@@ -1,4 +1,6 @@
 <?php
+declare(strict_types = 1);
+
 namespace FioApi;
 
 class Account
@@ -18,15 +20,13 @@ class Account
     /** @var string */
     protected $bic;
 
-    /**
-     * @param string $accountNumber
-     * @param string $bankCode
-     * @param string $currency
-     * @param string $iban
-     * @param string $bic
-     */
-    public function __construct($accountNumber, $bankCode, $currency, $iban, $bic)
-    {
+    public function __construct(
+        string $accountNumber,
+        string $bankCode,
+        string $currency,
+        string $iban,
+        string $bic
+    ) {
         $this->accountNumber = $accountNumber;
         $this->bankCode = $bankCode;
         $this->currency = $currency;
@@ -34,42 +34,27 @@ public function __construct($accountNumber, $bankCode, $currency, $iban, $bic)
         $this->bic = $bic;
     }
 
-    /**
-     * @return string
-     */
-    public function getAccountNumber()
+    public function getAccountNumber(): string
     {
         return $this->accountNumber;
     }
 
-    /**
-     * @return string
-     */
-    public function getBankCode()
+    public function getBankCode(): string
     {
         return $this->bankCode;
     }
 
-    /**
-     * @return string
-     */
-    public function getCurrency()
+    public function getCurrency(): string
     {
         return $this->currency;
     }
 
-    /**
-     * @return string
-     */
-    public function getIban()
+    public function getIban(): string
     {
         return $this->iban;
     }
 
-    /**
-     * @return string
-     */
-    public function getBic()
+    public function getBic(): string
     {
         return $this->bic;
     }
diff --git a/src/FioApi/Downloader.php b/src/FioApi/Downloader.php
index 98aa931..458150a 100644
--- a/src/FioApi/Downloader.php
+++ b/src/FioApi/Downloader.php
@@ -1,8 +1,11 @@
 <?php
+declare(strict_types = 1);
+
 namespace FioApi;
 
 use FioApi\Exceptions\InternalErrorException;
 use FioApi\Exceptions\TooGreedyException;
+use GuzzleHttp\ClientInterface;
 use Psr\Http\Message\ResponseInterface;
 
 class Downloader
@@ -16,30 +19,28 @@ class Downloader
     /** @var string */
     protected $certificatePath;
 
-    /**
-     * @param string $token
-     */
-    public function __construct($token, \GuzzleHttp\ClientInterface $client = null)
-    {
+    public function __construct(
+        string $token,
+        \GuzzleHttp\ClientInterface $client = null
+    ) {
         $this->urlBuilder = new UrlBuilder($token);
         $this->client = $client;
     }
 
-    /**
-     * @param string $path
-     */
-    public function setCertificatePath($path)
+    public function setCertificatePath(string $path)
     {
         $this->certificatePath = $path;
     }
 
-    public function getCertificatePath()
+    public function getCertificatePath(): string
     {
         if ($this->certificatePath) {
             return $this->certificatePath;
         }
 
-        if (class_exists('\Kdyby\CurlCaBundle\CertificateHelper')) {
+        if (class_exists('\Composer\CaBundle\CaBundle')) {
+            return \Composer\CaBundle\CaBundle::getSystemCaRootBundlePath();
+        } elseif (class_exists('\Kdyby\CurlCaBundle\CertificateHelper')) {
             return \Kdyby\CurlCaBundle\CertificateHelper::getCaInfoFile();
         }
 
@@ -47,10 +48,7 @@ public function getCertificatePath()
         return __DIR__ . '/keys/Geotrust_PCA_G3_Root.pem';
     }
 
-    /**
-     * @return \GuzzleHttp\ClientInterface
-     */
-    public function getClient()
+    public function getClient(): ClientInterface
     {
         if (!$this->client) {
             $this->client = new \GuzzleHttp\Client();
@@ -58,12 +56,7 @@ public function getClient()
         return $this->client;
     }
 
-    /**
-     * @param \DateTime $from
-     * @param \DateTime $to
-     * @return TransactionList
-     */
-    public function downloadFromTo(\DateTime $from, \DateTime $to)
+    public function downloadFromTo(\DateTimeInterface $from, \DateTimeInterface $to): TransactionList
     {
         $client = $this->getClient();
         $url = $this->urlBuilder->buildPeriodsUrl($from, $to);
@@ -85,15 +78,11 @@ public function downloadFromTo(\DateTime $from, \DateTime $to)
             throw $e;
         }
 
-        return TransactionList::create(json_decode($response->getBody())->accountStatement);
+        return TransactionList::create(json_decode($response->getBody()->getContents())->accountStatement);
     }
 
-    /**
-     * @param \DateTime $since
-     * @return TransactionList
-     */
-    public function downloadSince(\DateTime $since)
+    public function downloadSince(\DateTimeInterface $since): TransactionList
     {
-        return $this->downloadFromTo($since, new \DateTime());
+        return $this->downloadFromTo($since, new \DateTimeImmutable());
     }
 }
diff --git a/src/FioApi/Exceptions/InternalErrorException.php b/src/FioApi/Exceptions/InternalErrorException.php
index b4ead6f..d82f862 100644
--- a/src/FioApi/Exceptions/InternalErrorException.php
+++ b/src/FioApi/Exceptions/InternalErrorException.php
@@ -1,4 +1,6 @@
 <?php
+declare(strict_types = 1);
+
 namespace FioApi\Exceptions;
 
 class InternalErrorException extends \RuntimeException
diff --git a/src/FioApi/Exceptions/MissingTokenException.php b/src/FioApi/Exceptions/MissingTokenException.php
index 2a0a4d0..2815834 100644
--- a/src/FioApi/Exceptions/MissingTokenException.php
+++ b/src/FioApi/Exceptions/MissingTokenException.php
@@ -1,4 +1,6 @@
 <?php
+declare(strict_types = 1);
+
 namespace FioApi\Exceptions;
 
 class MissingTokenException extends \UnexpectedValueException
diff --git a/src/FioApi/Exceptions/TooGreedyException.php b/src/FioApi/Exceptions/TooGreedyException.php
index db92870..5cd6f40 100644
--- a/src/FioApi/Exceptions/TooGreedyException.php
+++ b/src/FioApi/Exceptions/TooGreedyException.php
@@ -1,4 +1,6 @@
 <?php
+declare(strict_types = 1);
+
 namespace FioApi\Exceptions;
 
 class TooGreedyException extends \RuntimeException
diff --git a/src/FioApi/Transaction.php b/src/FioApi/Transaction.php
index 7abe1e1..da429a3 100644
--- a/src/FioApi/Transaction.php
+++ b/src/FioApi/Transaction.php
@@ -1,12 +1,14 @@
 <?php
+declare(strict_types = 1);
+
 namespace FioApi;
 
 class Transaction
 {
-    /** @var int */
+    /** @var string */
     protected $id;
 
-    /** @var \DateTime */
+    /** @var \DateTimeImmutable */
     protected $date;
 
     /** @var float */
@@ -15,63 +17,63 @@ class Transaction
     /** @var string */
     protected $currency;
 
-    /** @var string */
+    /** @var string|null */
     protected $senderAccountNumber;
 
-    /** @var string */
+    /** @var string|null */
     protected $senderBankCode;
 
-    /** @var string */
+    /** @var string|null */
     protected $senderBankName;
 
-    /** @var int */
+    /** @var string|null */
     protected $constantSymbol;
 
-    /** @var string */
+    /** @var string|null */
     protected $variableSymbol;
 
-    /** @var int */
+    /** @var string|null */
     protected $specificSymbol;
 
-    /** @var string */
+    /** @var string|null */
     protected $userIdentity;
 
-    /** @var string */
+    /** @var string|null */
     protected $userMessage;
 
     /** @var string */
     protected $transactionType;
 
-    /** @var string */
+    /** @var string|null */
     protected $performedBy;
 
-    /** @var string */
+    /** @var string|null */
     protected $comment;
 
-    /** @var string */
+    /** @var float|null */
     protected $paymentOrderId;
 
-    /** @var string */
+    /** @var string|null */
     protected $specification;
 
     protected function __construct(
-        $id,
-        $date,
-        $amount,
-        $currency,
-        $senderAccountNumber,
-        $senderBankCode,
-        $senderBankName,
-        $constantSymbol,
-        $variableSymbol,
-        $specificSymbol,
-        $userIdentity,
-        $userMessage,
-        $transactionType,
-        $performedBy,
-        $comment,
-        $paymentOrderId,
-        $specification
+        string $id,
+        \DateTimeImmutable $date,
+        float $amount,
+        string $currency,
+        ?string $senderAccountNumber,
+        ?string $senderBankCode,
+        ?string $senderBankName,
+        ?string $constantSymbol,
+        ?string $variableSymbol,
+        ?string $specificSymbol,
+        ?string $userIdentity,
+        ?string $userMessage,
+        string $transactionType,
+        ?string $performedBy,
+        ?string $comment,
+        ?float $paymentOrderId,
+        ?string $specification
     ) {
         $this->id = $id;
         $this->date = $date;
@@ -96,11 +98,11 @@ protected function __construct(
      * @param \stdClass $data Transaction data from JSON API response
      * @return Transaction
      */
-    public static function create(\stdClass $data)
+    public static function create(\stdClass $data): Transaction
     {
         return new self(
-            $data->column22->value, //ID pohybu
-            new \DateTime($data->column0->value), //Datum
+            (string) $data->column22->value, //ID pohybu
+            new \DateTimeImmutable($data->column0->value), //Datum
             $data->column1->value, //Objem
             $data->column14->value, //Měna
             !empty($data->column2) ? $data->column2->value : null, //Protiúčet
@@ -119,138 +121,87 @@ public static function create(\stdClass $data)
         );
     }
 
-    /**
-     * @return int
-     */
-    public function getId()
+    public function getId(): string
     {
         return $this->id;
     }
 
-    /**
-     * @return \DateTime
-     */
-    public function getDate()
+    public function getDate(): \DateTimeImmutable
     {
         return $this->date;
     }
 
-    /**
-     * @return float
-     */
-    public function getAmount()
+    public function getAmount(): float
     {
         return $this->amount;
     }
 
-    /**
-     * @return string
-     */
-    public function getCurrency()
+    public function getCurrency(): string
     {
         return $this->currency;
     }
 
-    /**
-     * @return string
-     */
-    public function getSenderAccountNumber()
+    public function getSenderAccountNumber(): ?string
     {
         return $this->senderAccountNumber;
     }
 
-    /**
-     * @return string
-     */
-    public function getSenderBankCode()
+    public function getSenderBankCode(): ?string
     {
         return $this->senderBankCode;
     }
 
-    /**
-     * @return string
-     */
-    public function getSenderBankName()
+    public function getSenderBankName(): ?string
     {
         return $this->senderBankName;
     }
 
-    /**
-     * @return int
-     */
-    public function getConstantSymbol()
+    public function getConstantSymbol(): ?string
     {
         return $this->constantSymbol;
     }
 
-    /**
-     * @return string
-     */
-    public function getVariableSymbol()
+    public function getVariableSymbol(): ?string
     {
         return $this->variableSymbol;
     }
 
-    /**
-     * @return int
-     */
-    public function getSpecificSymbol()
+    public function getSpecificSymbol(): ?string
     {
         return $this->specificSymbol;
     }
 
-    /**
-     * @return string
-     */
-    public function getUserIdentity()
+    public function getUserIdentity(): ?string
     {
         return $this->userIdentity;
     }
 
-    /**
-     * @return string
-     */
-    public function getUserMessage()
+    public function getUserMessage(): ?string
     {
         return $this->userMessage;
     }
 
-    /**
-     * @return string
-     */
-    public function getTransactionType()
+    public function getTransactionType(): string
     {
         return $this->transactionType;
     }
 
-    /**
-     * @return string
-     */
-    public function getPerformedBy()
+    public function getPerformedBy(): ?string
     {
         return $this->performedBy;
     }
 
-    /**
-     * @return string
-     */
-    public function getComment()
+    public function getComment(): ?string
     {
         return $this->comment;
     }
 
-    /**
-     * @return string
-     */
-    public function getPaymentOrderId()
+    public function getPaymentOrderId(): ?float
     {
         return $this->paymentOrderId;
     }
 
-    /**
-     * @return string
-     */
-    public function getSpecification()
+    public function getSpecification(): ?string
     {
         return $this->specification;
     }
diff --git a/src/FioApi/TransactionList.php b/src/FioApi/TransactionList.php
index 54dede1..5ed1e94 100644
--- a/src/FioApi/TransactionList.php
+++ b/src/FioApi/TransactionList.php
@@ -1,4 +1,6 @@
 <?php
+declare(strict_types = 1);
+
 namespace FioApi;
 
 class TransactionList
@@ -9,16 +11,16 @@ class TransactionList
     /** @var float */
     protected $closingBalance;
 
-    /** @var \DateTime */
+    /** @var \DateTimeImmutable */
     protected $dateStart;
 
-    /** @var \DateTime */
+    /** @var \DateTimeImmutable */
     protected $dateEnd;
 
-    /** @var int */
+    /** @var float */
     protected $idFrom;
 
-    /** @var int */
+    /** @var float */
     protected $idTo;
 
     /** @var int */
@@ -30,24 +32,14 @@ class TransactionList
     /** @var Transaction[] */
     protected $transactions = [];
 
-    /**
-     * @param float $openingBalance
-     * @param float $closingBalance
-     * @param \DateTime $dateStart
-     * @param \DateTime $dateEnd
-     * @param int $idFrom
-     * @param int $idTo
-     * @param int $idLastDownload
-     * @param Account $account
-     */
     protected function __construct(
-        $openingBalance,
-        $closingBalance,
-        \DateTime $dateStart,
-        \DateTime $dateEnd,
-        $idFrom,
-        $idTo,
-        $idLastDownload,
+        float $openingBalance,
+        float $closingBalance,
+        \DateTimeImmutable $dateStart,
+        \DateTimeImmutable $dateEnd,
+        ?float $idFrom,
+        ?float $idTo,
+        ?int $idLastDownload,
         Account $account
     ) {
         $this->openingBalance = $openingBalance;
@@ -72,7 +64,7 @@ protected function addTransaction(Transaction $transaction)
      * @param \stdClass $data Data from JSON API response
      * @return TransactionList
      */
-    public static function create(\stdClass $data)
+    public static function create(\stdClass $data): TransactionList
     {
         $account = new Account(
             $data->info->accountId,
@@ -85,8 +77,8 @@ public static function create(\stdClass $data)
         $transactionList = new self(
             $data->info->openingBalance,
             $data->info->closingBalance,
-            new \DateTime($data->info->dateStart),
-            new \DateTime($data->info->dateEnd),
+            new \DateTimeImmutable($data->info->dateStart),
+            new \DateTimeImmutable($data->info->dateEnd),
             $data->info->idFrom,
             $data->info->idTo,
             $data->info->idLastDownload,
@@ -100,66 +92,42 @@ public static function create(\stdClass $data)
         return $transactionList;
     }
 
-    /**
-     * @return float
-     */
-    public function getOpeningBalance()
+    public function getOpeningBalance(): float
     {
         return $this->openingBalance;
     }
 
-    /**
-     * @return float
-     */
-    public function getClosingBalance()
+    public function getClosingBalance(): float
     {
         return $this->closingBalance;
     }
 
-    /**
-     * @return \DateTime
-     */
-    public function getDateStart()
+    public function getDateStart(): \DateTimeImmutable
     {
         return $this->dateStart;
     }
 
-    /**
-     * @return \DateTime
-     */
-    public function getDateEnd()
+    public function getDateEnd(): \DateTimeImmutable
     {
         return $this->dateEnd;
     }
 
-    /**
-     * @return int
-     */
-    public function getIdFrom()
+    public function getIdFrom(): ?float
     {
         return $this->idFrom;
     }
 
-    /**
-     * @return int
-     */
-    public function getIdTo()
+    public function getIdTo(): ?float
     {
         return $this->idTo;
     }
 
-    /**
-     * @return int
-     */
-    public function getIdLastDownload()
+    public function getIdLastDownload(): ?int
     {
         return $this->idLastDownload;
     }
 
-    /**
-     * @return Account
-     */
-    public function getAccount()
+    public function getAccount(): Account
     {
         return $this->account;
     }
@@ -167,7 +135,7 @@ public function getAccount()
     /**
      * @return Transaction[]
      */
-    public function getTransactions()
+    public function getTransactions(): array
     {
         return $this->transactions;
     }
diff --git a/src/FioApi/UrlBuilder.php b/src/FioApi/UrlBuilder.php
index 8a065f1..cf1a731 100644
--- a/src/FioApi/UrlBuilder.php
+++ b/src/FioApi/UrlBuilder.php
@@ -1,4 +1,6 @@
 <?php
+declare(strict_types = 1);
+
 namespace FioApi;
 
 use FioApi\Exceptions\MissingTokenException;
@@ -7,31 +9,20 @@ class UrlBuilder
 {
     const BASE_URL = 'https://www.fio.cz/ib_api/rest/';
 
-    /**
-     * @var string
-     */
+    /** @var string */
     protected $token;
 
-    /**
-     * @param string $token
-     */
-    public function __construct($token)
+    public function __construct(string $token)
     {
         $this->setToken($token);
     }
 
-    /**
-     * @return string
-     */
-    public function getToken()
+    public function getToken(): string
     {
         return $this->token;
     }
 
-    /**
-     * @param string $token
-     */
-    public function setToken($token)
+    public function setToken(string $token)
     {
         if (!$token) {
             throw new MissingTokenException(
@@ -41,12 +32,7 @@ public function setToken($token)
         $this->token = $token;
     }
 
-    /**
-     * @param \DateTime $from
-     * @param \DateTime $to
-     * @return string
-     */
-    public function buildPeriodsUrl(\DateTime $from, \DateTime $to)
+    public function buildPeriodsUrl(\DateTimeInterface $from, \DateTimeInterface $to): string
     {
         return sprintf(
             self::BASE_URL . 'periods/%s/%s/%s/transactions.json',
diff --git a/tests/FioApi/AccountTest.php b/tests/FioApi/AccountTest.php
index ef73bcb..d9a257a 100644
--- a/tests/FioApi/AccountTest.php
+++ b/tests/FioApi/AccountTest.php
@@ -1,8 +1,9 @@
 <?php
+declare(strict_types = 1);
 
 namespace FioApi;
 
-class AccountTest extends \PHPUnit_Framework_TestCase
+class AccountTest extends \PHPUnit\Framework\TestCase
 {
     public function testAccountValuesAreProperlySet()
     {
@@ -13,10 +14,10 @@ public function testAccountValuesAreProperlySet()
             'CZ9820100000000214498596',
             'FIOBCZPPXXX'
         );
-        $this->assertEquals('214498596', $account->getAccountNumber());
-        $this->assertEquals('2010', $account->getBankCode());
-        $this->assertEquals('CZK', $account->getCurrency());
-        $this->assertEquals('CZ9820100000000214498596', $account->getIban());
-        $this->assertEquals('FIOBCZPPXXX', $account->getBic());
+        $this->assertSame('214498596', $account->getAccountNumber());
+        $this->assertSame('2010', $account->getBankCode());
+        $this->assertSame('CZK', $account->getCurrency());
+        $this->assertSame('CZ9820100000000214498596', $account->getIban());
+        $this->assertSame('FIOBCZPPXXX', $account->getBic());
     }
 }
diff --git a/tests/FioApi/DownloaderTest.php b/tests/FioApi/DownloaderTest.php
index 5985d1b..e4d5df5 100644
--- a/tests/FioApi/DownloaderTest.php
+++ b/tests/FioApi/DownloaderTest.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types = 1);
 
 namespace FioApi;
 
@@ -8,43 +9,43 @@
 use GuzzleHttp\HandlerStack;
 use GuzzleHttp\Psr7\Response;
 
-class DownloaderTest extends \PHPUnit_Framework_TestCase
+class DownloaderTest extends \PHPUnit\Framework\TestCase
 {
-    /**
-     * @expectedException \FioApi\Exceptions\TooGreedyException
-     */
     public function testNotRespectingTheTimeoutResultsInTooGreedyException()
     {
         $handler = HandlerStack::create(new MockHandler([
             new Response(409),
         ]));
         $downloader = new Downloader('testToken', new Client(['handler' => $handler]));
-        $downloader->downloadSince(new \DateTime('-1 week'));
+
+        $this->expectException(\FioApi\Exceptions\TooGreedyException::class);
+
+        $downloader->downloadSince(new \DateTimeImmutable('-1 week'));
     }
 
-    /**
-     * @expectedException \FioApi\Exceptions\InternalErrorException
-     */
     public function testInvalidTokenResultsInInternalErrorException()
     {
         $handler = HandlerStack::create(new MockHandler([
             new Response(500),
         ]));
         $downloader = new Downloader('invalidToken', new Client(['handler' => $handler]));
-        $downloader->downloadSince(new \DateTime('-1 week'));
+
+        $this->expectException(\FioApi\Exceptions\InternalErrorException::class);
+
+        $downloader->downloadSince(new \DateTimeImmutable('-1 week'));
     }
 
-    /**
-     * @expectedException \GuzzleHttp\Exception\BadResponseException
-     * @expectedExceptionCode 418
-     */
     public function testUnknownResponseCodePassesOriginalException()
     {
         $handler = HandlerStack::create(new MockHandler([
             new Response(418),
         ]));
         $downloader = new Downloader('validToken', new Client(['handler' => $handler]));
-        $downloader->downloadSince(new \DateTime('-1 week'));
+
+        $this->expectException(\GuzzleHttp\Exception\BadResponseException::class);
+        $this->expectExceptionCode(418);
+
+        $downloader->downloadSince(new \DateTimeImmutable('-1 week'));
     }
 
     public function testDownloaderDownloadsData()
@@ -53,14 +54,16 @@ public function testDownloaderDownloadsData()
             new Response(200, [], file_get_contents(__DIR__ . '/data/example-response.json')),
         ]));
         $downloader = new Downloader('validToken', new Client(['handler' => $handler]));
-        $transactionList = $downloader->downloadSince(new \DateTime('-1 week'));
-        $this->assertInstanceOf('\FioApi\TransactionList', $transactionList);
+
+        $transactionList = $downloader->downloadSince(new \DateTimeImmutable('-1 week'));
+
+        $this->assertInstanceOf(TransactionList::class, $transactionList);
     }
 
     public function testDownloaderSetCertificatePath()
     {
         $downloader = new Downloader('validToken');
         $downloader->setCertificatePath('foo.pem');
-        $this->assertEquals('foo.pem', $downloader->getCertificatePath());
+        $this->assertSame('foo.pem', $downloader->getCertificatePath());
     }
 }
diff --git a/tests/FioApi/TransactionListTest.php b/tests/FioApi/TransactionListTest.php
index dbf0128..39b817b 100644
--- a/tests/FioApi/TransactionListTest.php
+++ b/tests/FioApi/TransactionListTest.php
@@ -1,8 +1,9 @@
 <?php
+declare(strict_types = 1);
 
 namespace FioApi;
 
-class TransactionListTest extends \PHPUnit_Framework_TestCase
+class TransactionListTest extends \PHPUnit\Framework\TestCase
 {
     public function testTransactionListValuesAreProperlySet()
     {
@@ -10,14 +11,31 @@ public function testTransactionListValuesAreProperlySet()
 
         $transactionList = TransactionList::create($transactionList->accountStatement);
 
-        $this->assertSame(500, $transactionList->getOpeningBalance());
-        $this->assertSame(1000, $transactionList->getClosingBalance());
-        $this->assertEquals(new \DateTime('2015-03-30+0200'), $transactionList->getDateStart());
-        $this->assertEquals(new \DateTime('2015-03-31+0200'), $transactionList->getDateEnd());
-        $this->assertSame(1111111111, $transactionList->getIdFrom());
-        $this->assertSame(1111111999, $transactionList->getIdTo());
+        $this->assertSame(500.0, $transactionList->getOpeningBalance());
+        $this->assertSame(1000.0, $transactionList->getClosingBalance());
+        $this->assertEquals(new \DateTimeImmutable('2015-03-30+0200'), $transactionList->getDateStart());
+        $this->assertEquals(new \DateTimeImmutable('2015-03-31+0200'), $transactionList->getDateEnd());
+        $this->assertSame((float) 1111111111, $transactionList->getIdFrom());
+        $this->assertSame((float) 1111111999, $transactionList->getIdTo());
         $this->assertSame(null, $transactionList->getIdLastDownload());
-        $this->assertInstanceOf('FioApi\Account', $transactionList->getAccount());
-        $this->assertInstanceOf('FioApi\Transaction', $transactionList->getTransactions()[0]);
+        $this->assertInstanceOf(Account::class, $transactionList->getAccount());
+        $this->assertInstanceOf(Transaction::class, $transactionList->getTransactions()[0]);
+    }
+
+    public function testEmptyTransactionList()
+    {
+        $transactionList = json_decode(file_get_contents(__DIR__ . '/data/example-empty-response.json'));
+
+        $transactionList = TransactionList::create($transactionList->accountStatement);
+
+        $this->assertSame(0.0, $transactionList->getOpeningBalance());
+        $this->assertSame(0.0, $transactionList->getClosingBalance());
+        $this->assertEquals(new \DateTimeImmutable('2017-08-06+0200'), $transactionList->getDateStart());
+        $this->assertEquals(new \DateTimeImmutable('2017-08-08+0200'), $transactionList->getDateEnd());
+        $this->assertNull($transactionList->getIdFrom());
+        $this->assertNull($transactionList->getIdTo());
+        $this->assertNull($transactionList->getIdLastDownload());
+        $this->assertInstanceOf(Account::class, $transactionList->getAccount());
+        $this->assertCount(0, $transactionList->getTransactions());
     }
 }
diff --git a/tests/FioApi/TransactionTest.php b/tests/FioApi/TransactionTest.php
index c4c5b46..6a31741 100644
--- a/tests/FioApi/TransactionTest.php
+++ b/tests/FioApi/TransactionTest.php
@@ -1,8 +1,9 @@
 <?php
+declare(strict_types = 1);
 
 namespace FioApi;
 
-class TransactionTest extends \PHPUnit_Framework_TestCase
+class TransactionTest extends \PHPUnit\Framework\TestCase
 {
     public function testAccountValuesAreProperlySet()
     {
@@ -10,8 +11,8 @@ public function testAccountValuesAreProperlySet()
 
         $transaction = Transaction::create($transaction);
 
-        $this->assertSame(1111111111, $transaction->getId());
-        $this->assertEquals(new \DateTime('2015-03-30+0200'), $transaction->getDate());
+        $this->assertSame('1111111111', $transaction->getId());
+        $this->assertEquals(new \DateTimeImmutable('2015-03-30+0200'), $transaction->getDate());
         $this->assertSame(127.0, $transaction->getAmount());
         $this->assertSame('CZK', $transaction->getCurrency());
         $this->assertSame('214498596', $transaction->getSenderAccountNumber());
@@ -25,7 +26,7 @@ public function testAccountValuesAreProperlySet()
         $this->assertSame('Bezhotovostní příjem', $transaction->getTransactionType());
         $this->assertSame(null, $transaction->getPerformedBy());
         $this->assertSame('Comment? Comment!', $transaction->getComment());
-        $this->assertSame(1111122222, $transaction->getPaymentOrderId());
+        $this->assertSame((float) 1111122222, $transaction->getPaymentOrderId());
         $this->assertSame('1500.00 EUR', $transaction->getSpecification());
     }
 }
diff --git a/tests/FioApi/UrlBuilderTest.php b/tests/FioApi/UrlBuilderTest.php
index 4e6ddd9..e1c38e2 100644
--- a/tests/FioApi/UrlBuilderTest.php
+++ b/tests/FioApi/UrlBuilderTest.php
@@ -1,36 +1,39 @@
 <?php
+declare(strict_types = 1);
 
 namespace FioApi;
 
-class UrlBuilderTest extends \PHPUnit_Framework_TestCase
+class UrlBuilderTest extends \PHPUnit\Framework\TestCase
 {
-    /**
-     * @expectedException \FioApi\Exceptions\MissingTokenException
-     */
     public function testMissingTokenExceptionIsThrownForEmptyToken()
     {
+        $this->expectException(\FioApi\Exceptions\MissingTokenException::class);
+
         new UrlBuilder('');
     }
 
     public function testTokenCanBeSetThroughConstructor()
     {
         $urlBuilder = new UrlBuilder('token1');
-        $this->assertEquals('token1', $urlBuilder->getToken());
+        $this->assertSame('token1', $urlBuilder->getToken());
     }
 
     public function testTokenCanBeChangedThroughSetter()
     {
         $urlBuilder = new UrlBuilder('token1');
         $urlBuilder->setToken('token2');
-        $this->assertEquals('token2', $urlBuilder->getToken());
+        $this->assertSame('token2', $urlBuilder->getToken());
     }
 
     public function testBuildPeriodsUrlReturnValidUrl()
     {
         $urlBuilder = new UrlBuilder('token1');
-        $this->assertEquals(
+        $this->assertSame(
             'https://www.fio.cz/ib_api/rest/periods/token1/2015-03-25/2015-03-31/transactions.json',
-            $urlBuilder->buildPeriodsUrl(new \DateTime('2015-03-25'), new \DateTime('2015-03-31'))
+            $urlBuilder->buildPeriodsUrl(
+                new \DateTimeImmutable('2015-03-25'),
+                new \DateTimeImmutable('2015-03-31')
+            )
         );
     }
 }
diff --git a/tests/FioApi/data/example-empty-response.json b/tests/FioApi/data/example-empty-response.json
new file mode 100644
index 0000000..fccd0d8
--- /dev/null
+++ b/tests/FioApi/data/example-empty-response.json
@@ -0,0 +1,23 @@
+{
+  "accountStatement": {
+    "info": {
+      "accountId": "260000000",
+      "bankId": "2010",
+      "currency": "EUR",
+      "iban": "CZ652010000000000",
+      "bic": "FIOBCZPPXXX",
+      "openingBalance": 0.00,
+      "closingBalance": 0.00,
+      "dateStart": "2017-08-06+0200",
+      "dateEnd": "2017-08-08+0200",
+      "yearList": null,
+      "idList": null,
+      "idFrom": null,
+      "idTo": null,
+      "idLastDownload": null
+    },
+    "transactionList": {
+      "transaction": []
+    }
+  }
+}
diff --git a/tests/bootstrap.php b/tests/bootstrap.php
index 52fb375..24a050e 100644
--- a/tests/bootstrap.php
+++ b/tests/bootstrap.php
@@ -1,3 +1,5 @@
 <?php
+declare(strict_types = 1);
+
 $loader = require __DIR__ . '/../vendor/autoload.php';
 $loader->addPsr4('FioApi\\', __DIR__ . '/FioApi');