diff --git a/.travis.yml b/.travis.yml
index 7896b6d..e196514 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,16 +1,14 @@
 language: php
 php:
-- '5.6'
 - '7.0'
 - '7.1'
+- '7.2'
 env:
   - INTL_VERSION="2.3.*"
   - INTL_VERSION="3.0.*"
   - INTL_VERSION="4.0.*"
 matrix:
   exclude:
-  - php: '5.6'
-    env: INTL_VERSION="4.0.*"
   - php: '7.0'
     env: INTL_VERSION="4.0.*"
 before_script:
diff --git a/composer.json b/composer.json
index 1cff74b..8a92f14 100644
--- a/composer.json
+++ b/composer.json
@@ -13,7 +13,7 @@
     }
   ],
   "require": {
-    "php": "^5.6|^7",
+    "php": "^7",
     "symfony/intl": "^2.0 || ^3.0 || ^4.0"
   },
   "require-dev": {
diff --git a/src/Money.php b/src/Money.php
index 97c483a..348f0ce 100644
--- a/src/Money.php
+++ b/src/Money.php
@@ -17,10 +17,10 @@ class Money
     private $currency;
 
     /**
-     * @param float $amount
+     * @param float|int|string $amount
      * @param string $currency
      */
-    public function __construct($amount, $currency)
+    public function __construct($amount, string $currency)
     {
         if (!is_numeric($amount)) {
             throw new InvalidArgumentException('Money only accepts numeric amounts');
@@ -33,29 +33,20 @@ public function __construct($amount, $currency)
         $this->currency = $currency;
     }
 
-    /**
-     * @return string
-     */
-    public function __toString()
+    public function __toString(): string
     {
         return $this->format();
     }
 
     /**
      * Returns a positive clone of Money object
-     *
-     * @return static
      */
-    public function abs()
+    public function abs(): Money
     {
         return new static(abs($this->amount), $this->currency);
     }
 
-    /**
-     * @param Money $money
-     * @return static
-     */
-    public function add(Money $money)
+    public function add(Money $money): Money
     {
         $this->assertCurrencyMatches($money);
 
@@ -66,7 +57,7 @@ public function add(Money $money)
      * @param float $operator
      * @return static
      */
-    public function divide($operator)
+    public function divide($operator): Money
     {
         if ($operator == 0) {
             throw new InvalidArgumentException('Cannot divide by zero');
@@ -80,7 +71,7 @@ public function divide($operator)
      * @param bool $displayCountryForUS Set to true if you would like 'US$' instead of just '$'
      * @return string
      */
-    public function format($displayCountryForUS = false)
+    public function format(bool $displayCountryForUS = false): string
     {
         $formatter = new NumberFormatter('en', NumberFormatter::CURRENCY);
 
@@ -96,10 +87,8 @@ public function format($displayCountryForUS = false)
     /**
      * Returns a rounded number without currency
      * If the number is negative, the currency is within parentheses
-     *
-     * @return string
      */
-    public function formatForAccounting()
+    public function formatForAccounting(): string
     {
         $amount = $this->getRoundedAmount();
         $negative = 0 > $amount;
@@ -113,10 +102,8 @@ public function formatForAccounting()
     /**
      * Returns a string consisting of the currency symbol, a rounded int and a suffix
      * e.g. $33k instead of $3321.12
-     *
-     * @return string
      */
-    public function formatShorthand()
+    public function formatShorthand(): string
     {
         $amount = $this->amount;
         $negative = 0 > $amount;
@@ -135,7 +122,7 @@ public function formatShorthand()
      * @param bool $displayCountryForUS Set to true if you would like 'US$' instead of just '$'
      * @return string
      */
-    public function formatWithSign($displayCountryForUS = false)
+    public function formatWithSign(bool $displayCountryForUS = false): string
     {
         $string = $this->format($displayCountryForUS);
 
@@ -146,28 +133,20 @@ public function formatWithSign($displayCountryForUS = false)
         return '+' . $string;
     }
 
-    /**
-     * @return float
-     */
-    public function getAmount()
+    public function getAmount(): float
     {
         return $this->amount;
     }
 
-    /**
-     * @return string
-     */
-    public function getCurrency()
+    public function getCurrency(): string
     {
         return $this->currency;
     }
 
     /**
      * Returns the amount rounded to the correct number of decimal places for that currency
-     *
-     * @return float
      */
-    public function getRoundedAmount()
+    public function getRoundedAmount(): float
     {
         $fractionDigits = Intl::getCurrencyBundle()->getFractionDigits($this->currency);
         $roundingIncrement = Intl::getCurrencyBundle()->getRoundingIncrement($this->currency);
@@ -185,10 +164,8 @@ public function getRoundedAmount()
 
     /**
      * Invert the amount
-     *
-     * @return static
      */
-    public function inv()
+    public function inv(): Money
     {
         return new static(-$this->amount, $this->currency);
     }
@@ -197,7 +174,7 @@ public function inv()
      * @param float $operator
      * @return static
      */
-    public function multiply($operator)
+    public function multiply($operator): Money
     {
         return new static($this->amount * $operator, $this->currency);
     }
@@ -208,17 +185,15 @@ public function multiply($operator)
      * @param float $percentage
      * @return static
      */
-    public function percentage($percentage)
+    public function percentage($percentage): Money
     {
         return new static(($this->amount * $percentage) / 100, $this->currency);
     }
 
     /**
      * Returns rounded clone of Money object, rounded to the correct number of decimal places for that currency
-     *
-     * @return static
      */
-    public function round()
+    public function round(): Money
     {
         return new static($this->getRoundedAmount(), $this->currency);
     }
@@ -232,9 +207,9 @@ public function round()
      *
      * @param float[] $percentages An array of percentages that must total 100 or less
      * @param bool $round
-     * @return array
+     * @return Money[]
      */
-    public function split(array $percentages, $round = true)
+    public function split(array $percentages, bool $round = true): array
     {
         $totalPercentage = array_sum($percentages);
         if ($totalPercentage > 100) {
@@ -278,7 +253,7 @@ public function split(array $percentages, $round = true)
      * @param Money $money
      * @return static
      */
-    public function sub(Money $money)
+    public function sub(Money $money): Money
     {
         $this->assertCurrencyMatches($money);
 
diff --git a/tests/MoneyTest.php b/tests/MoneyTest.php
index 221cc9b..985aa07 100644
--- a/tests/MoneyTest.php
+++ b/tests/MoneyTest.php
@@ -7,7 +7,7 @@
 
 class MoneyTest extends PHPUnit_Framework_TestCase
 {
-    public function amountDataProvider()
+    public function amountDataProvider(): array
     {
         return [
             [1000.00, 1000.00],
@@ -27,7 +27,7 @@ public function testCanRetrieveAmount($amount, $expected)
         $this->assertEquals($expected, $money->getAmount());
     }
 
-    public function currencyCodeDataProvider()
+    public function currencyCodeDataProvider(): array
     {
         return [
             ['USD'],
@@ -41,7 +41,7 @@ public function currencyCodeDataProvider()
      * @dataProvider currencyCodeDataProvider
      * @param string $currencyCode
      */
-    public function testCanRetrieveCurrency($currencyCode)
+    public function testCanRetrieveCurrency(string $currencyCode)
     {
         $money = new Money(1000, $currencyCode);
         $this->assertEquals($currencyCode, $money->getCurrency());
@@ -85,7 +85,7 @@ public function testAbsoluteMoney($amount, $expected)
         $this->assertEquals($expected, $money->abs()->getAmount());
     }
 
-    public function invertedAmountDataProvider()
+    public function invertedAmountDataProvider(): array
     {
         return [
             ['-9.9999', 9.9999],
@@ -156,7 +156,7 @@ public function testMultiplying()
         $this->assertEquals(30, $money->multiply(3)->getAmount());
     }
 
-    public function formattingDataProvider()
+    public function formattingDataProvider(): array
     {
         return [
             ['10.000', 'USD', '$10.00'],
@@ -176,13 +176,13 @@ public function formattingDataProvider()
      * @param string $currencyCode
      * @param string $expected
      */
-    public function testFormatting($amount, $currencyCode, $expected)
+    public function testFormatting($amount, string $currencyCode, $expected)
     {
         $money = new Money($amount, $currencyCode);
         $this->assertEquals($expected, (string)$money);
     }
 
-    public function manualFormattingDataProvider()
+    public function manualFormattingDataProvider(): array
     {
         return [
             [-10, 'USD', false, '-$10.00'],
@@ -196,15 +196,16 @@ public function manualFormattingDataProvider()
      * @dataProvider manualFormattingDataProvider
      * @param mixed $amount
      * @param string $currencyCode
+     * @param bool $displayCountryForUS
      * @param string $expected
      */
-    public function testManualFormatting($amount, $currencyCode, $displayCountryForUS, $expected)
+    public function testManualFormatting($amount, string $currencyCode, bool $displayCountryForUS, string $expected)
     {
         $money = new Money($amount, $currencyCode);
         $this->assertEquals($expected, $money->format($displayCountryForUS));
     }
 
-    public function forcedPlusFormattingDataProvider()
+    public function forcedPlusFormattingDataProvider(): array
     {
         return [
             [0, 'USD', false, '$0.00'],
@@ -223,13 +224,13 @@ public function forcedPlusFormattingDataProvider()
      * @param bool $displayCountryForUS
      * @param string $expected
      */
-    public function testForcePlusFormatting($amount, $currencyCode, $displayCountryForUS, $expected)
+    public function testForcePlusFormatting($amount, string $currencyCode, bool $displayCountryForUS, string $expected)
     {
         $money = new Money($amount, $currencyCode);
         $this->assertEquals($expected, $money->formatWithSign($displayCountryForUS));
     }
 
-    public function accountingFormattingDataProvider()
+    public function accountingFormattingDataProvider(): array
     {
         return [
             [0, 'USD', '0.00'],
@@ -246,13 +247,13 @@ public function accountingFormattingDataProvider()
      * @param string $currencyCode
      * @param string $expected
      */
-    public function testAccountingFormatting($amount, $currencyCode, $expected)
+    public function testAccountingFormatting($amount, string $currencyCode, string $expected)
     {
         $money = new Money($amount, $currencyCode);
         $this->assertSame($expected, $money->formatForAccounting());
     }
 
-    public function roundingDataProvider()
+    public function roundingDataProvider(): array
     {
         return [
             ['10.000', 'USD', 10.00],
@@ -272,14 +273,14 @@ public function roundingDataProvider()
      * @param string $currencyCode
      * @param string $expected
      */
-    public function testRoundedAmount($amount, $currencyCode, $expected)
+    public function testRoundedAmount($amount, string $currencyCode, $expected)
     {
         $money = new Money($amount, $currencyCode);
         $this->assertEquals($expected, $money->getRoundedAmount());
         $this->assertEquals($expected, $money->round()->getAmount());
     }
 
-    public function invalidCurrencyDataProvider()
+    public function invalidCurrencyDataProvider(): array
     {
         return [
             ['ZZZ'],
@@ -291,13 +292,13 @@ public function invalidCurrencyDataProvider()
      * @dataProvider invalidCurrencyDataProvider
      * @param string $currencyCode
      */
-    public function testValidCurrency($currencyCode)
+    public function testValidCurrency(string $currencyCode)
     {
         $this->expectException(InvalidArgumentException::class);
         new Money(10.000000, $currencyCode);
     }
 
-    public function percentageDataProvider()
+    public function percentageDataProvider(): array
     {
         return [
             ['2.222222', 50, 1.111111],
@@ -310,9 +311,9 @@ public function percentageDataProvider()
      * @dataProvider percentageDataProvider
      * @param mixed $amount
      * @param int $percentage
-     * @param string $expected
+     * @param float $expected
      */
-    public function testGettingPercentage($amount, $percentage, $expected)
+    public function testGettingPercentage($amount, int $percentage, float $expected)
     {
         $money = new Money($amount, 'USD');
         $this->assertEquals($expected, $money->percentage($percentage)->getAmount());