diff --git a/src/ArrayValidator.php b/src/ArrayValidator.php
index 9515494..8248f02 100644
--- a/src/ArrayValidator.php
+++ b/src/ArrayValidator.php
@@ -74,8 +74,8 @@ class ArrayValidator extends \Phramework\Validate\BaseValidator
      */
     public function __construct(
         int $minItems = 0,
-        int $maxItems = null,
-        $items = null,
+        ?int $maxItems = null,
+        ?BaseValidator $items = null,
         bool $uniqueItems = false
     ) {
         parent::__construct();
@@ -98,7 +98,6 @@ public function validate($value)
         $return = new Result($value, false);
 
         if (!is_array($value)) {
-            $return->exception = 'properties validation';
             //error
             $return->exception = new IncorrectParameterException(
                 'type',
diff --git a/src/BooleanValidator.php b/src/BooleanValidator.php
index e37e089..f0d93b3 100644
--- a/src/BooleanValidator.php
+++ b/src/BooleanValidator.php
@@ -38,8 +38,9 @@ class BooleanValidator extends \Phramework\Validate\BaseValidator
      * BooleanValidator constructor.
      * @param bool|null $default
      */
-    public function __construct(bool $default = null)
-    {
+    public function __construct(
+        ?bool $default = null
+    ) {
         parent::__construct();
 
         $this->default = $default;
diff --git a/src/DateValidator.php b/src/DateValidator.php
index 78a5997..6afffe6 100644
--- a/src/DateValidator.php
+++ b/src/DateValidator.php
@@ -51,8 +51,8 @@ class DateValidator extends \Phramework\Validate\StringValidator
      * ```
      */
     public function __construct(
-        string $formatMinimum = null,
-        string $formatMaximum = null
+        ?string $formatMinimum = null,
+        ?string $formatMaximum = null
     ) {
         parent::__construct();
 
diff --git a/src/DatetimeValidator.php b/src/DatetimeValidator.php
index c076e8c..b19ad4e 100644
--- a/src/DatetimeValidator.php
+++ b/src/DatetimeValidator.php
@@ -51,8 +51,8 @@ class DatetimeValidator extends \Phramework\Validate\StringValidator
      * ```
      */
     public function __construct(
-        string $formatMinimum = null,
-        string $formatMaximum = null
+        ?string $formatMinimum = null,
+        ?string $formatMaximum = null
     ) {
         parent::__construct();
 
diff --git a/src/EmailValidator.php b/src/EmailValidator.php
index 30795ca..8138bb6 100644
--- a/src/EmailValidator.php
+++ b/src/EmailValidator.php
@@ -41,8 +41,8 @@ class EmailValidator extends \Phramework\Validate\StringValidator
     protected static $type = 'email';
 
     public function __construct(
-        $minLength = 0,
-        $maxLength = null
+        int $minLength = 0,
+        ?int $maxLength = null
     ) {
         parent::__construct(
             $minLength,
@@ -62,7 +62,7 @@ public function validate($value)
         $return = parent::validate($value);
 
         //Apply additional rules
-        if ($return->status == true) {
+        if ($return->status === true) {
             if (filter_var($value, FILTER_VALIDATE_EMAIL) === false) {
                 //error
                 $return->exception = new IncorrectParameterException(
diff --git a/src/EnumValidator.php b/src/EnumValidator.php
index 06b4ab8..0d73ed2 100644
--- a/src/EnumValidator.php
+++ b/src/EnumValidator.php
@@ -46,7 +46,7 @@ class EnumValidator extends \Phramework\Validate\BaseValidator
 
     public function __construct(
         array $enum = [],
-        $validateType = false,
+        bool $validateType = false,
         $default = null
     ) {
         parent::__construct();
diff --git a/src/IntegerValidator.php b/src/IntegerValidator.php
index 4843a40..20cd52e 100644
--- a/src/IntegerValidator.php
+++ b/src/IntegerValidator.php
@@ -23,7 +23,7 @@
  * Integer validator
  * @uses \Phramework\Validate\Number As base implementation's rules to
  * validate that the value is a number and then applies additional rules
- * to validate that this is a interger
+ * to validate that this is a integer
  * @property integer|null minimum
  * @property integer|null maximum
  * @property boolean|null exclusiveMinimum
@@ -44,30 +44,18 @@ class IntegerValidator extends \Phramework\Validate\NumberValidator
     protected static $type = 'integer';
 
     /**
-     * @param integer|null $minimum
-     * @param integer|null $maximum
-     * @param boolean|null $exclusiveMinimum
-     * @param boolean|null $exclusiveMaximum
-     * @param integer|null $multipleOf
-     * @throws \Exception
+     * @throws \InvalidArgumentException When multipleOf is not positive integer
+     * @throws \DomainException
      */
     public function __construct(
-        int $minimum = null,
-        int $maximum = null,
+        ?int $minimum = null,
+        ?int $maximum = null,
         bool $exclusiveMinimum = null,
         bool $exclusiveMaximum = null,
         int $multipleOf = 1
     ) {
-        if ($minimum !== null && !is_int($minimum)) {
-            throw new \Exception('Minimum must be integer');
-        }
-
-        if ($maximum !== null && !is_int($maximum)) {
-            throw new \Exception('Maximum must be integer');
-        }
-
-        if (!is_int($multipleOf) || $multipleOf < 0) {
-            throw new \Exception('multipleOf must be a positive integer');
+        if ($multipleOf !== null && $multipleOf <= 0) {
+            throw new \InvalidArgumentException('multipleOf must be a positive integer');
         }
 
         parent::__construct(
diff --git a/src/NumberValidator.php b/src/NumberValidator.php
index 2d38a2d..1a8fde0 100644
--- a/src/NumberValidator.php
+++ b/src/NumberValidator.php
@@ -53,44 +53,23 @@ class NumberValidator extends \Phramework\Validate\BaseValidator
     protected static $type = 'number';
 
     /**
-     * @param float|null $minimum
-     * @param float|null $maximum
-     * @param bool|null  $exclusiveMinimum
-     * @param bool|null  $exclusiveMaximum
-     * @param float|null $multipleOf
-     * @throws \Exception
+     * @throws \DomainException When minimum is not less than the maximum
      */
     public function __construct(
-        float $minimum = null,
-        float $maximum = null,
-        bool $exclusiveMinimum = null,
-        bool $exclusiveMaximum = null,
-        float $multipleOf = null
+        ?float $minimum = null,
+        ?float $maximum = null,
+        ?bool $exclusiveMinimum = null,
+        ?bool $exclusiveMaximum = null,
+        ?float $multipleOf = null
     ) {
         parent::__construct();
 
-        if ($minimum !== null && !is_numeric($minimum)) {
-            throw new \Exception('Minimum must be numeric');
-        }
-
-        if ($maximum !== null && !is_numeric($maximum)) {
-            throw new \Exception('Maximum must be numeric');
-        }
-
         if ($maximum !== null && $minimum !== null && $maximum < $minimum) {
-            throw new \Exception('maximum cant be less than minimum');
-        }
-
-        if ($exclusiveMinimum !== null && !is_bool($exclusiveMinimum)) {
-            throw new \Exception('exclusiveMinimum must be boolean');
-        }
-
-        if ($exclusiveMaximum !== null && !is_bool($exclusiveMaximum)) {
-            throw new \Exception('exclusiveMaximum must be boolean');
+            throw new \DomainException('maximum cant be less than minimum');
         }
 
-        if ($multipleOf !== null && !is_numeric($multipleOf)) {
-            throw new \Exception('multipleOf must be numeric');
+        if ($multipleOf !== null && $multipleOf <= 0) {
+            throw new \InvalidArgumentException('multipleOf must be a positive number');
         }
 
         $this->minimum = $minimum;
diff --git a/src/ObjectValidator.php b/src/ObjectValidator.php
index 960c74b..63b81a8 100644
--- a/src/ObjectValidator.php
+++ b/src/ObjectValidator.php
@@ -79,7 +79,7 @@ public function __construct(
         array $required = [],
         $additionalProperties = true,
         int $minProperties = 0,
-        int $maxProperties = null,
+        ?int $maxProperties = null,
         \stdClass $dependencies = null,
         \stdClass $xVisibility = null,
         \stdClass $patternProperties = null
diff --git a/src/Result/Result.php b/src/Result/Result.php
index dd10503..9d2b017 100644
--- a/src/Result/Result.php
+++ b/src/Result/Result.php
@@ -49,7 +49,7 @@ class Result
     public function __construct(
         $value,
         bool $status = false,
-        \Exception $exception = null
+        ?\Exception $exception = null
     ) {
         $this->value     = $value;
         $this->status    = $status;
diff --git a/src/StringValidator.php b/src/StringValidator.php
index 0634cdb..cc390b6 100644
--- a/src/StringValidator.php
+++ b/src/StringValidator.php
@@ -59,8 +59,8 @@ class StringValidator extends \Phramework\Validate\BaseValidator
      */
     public function __construct(
         int $minLength = 0,
-        int $maxLength = null,
-        string $pattern = null,
+        ?int $maxLength = null,
+        ?string $pattern = null,
         bool $raw = false
     ) {
         parent::__construct();
diff --git a/src/URLValidator.php b/src/URLValidator.php
index f64d188..7aa339c 100644
--- a/src/URLValidator.php
+++ b/src/URLValidator.php
@@ -46,7 +46,7 @@ class URLValidator extends \Phramework\Validate\StringValidator
      */
     public function __construct(
         int $minLength = 0,
-        int $maxLength = null
+        ?int $maxLength = null
     ) {
         parent::__construct(
             $minLength,
diff --git a/src/UnsignedIntegerValidator.php b/src/UnsignedIntegerValidator.php
index d2f1083..296475b 100644
--- a/src/UnsignedIntegerValidator.php
+++ b/src/UnsignedIntegerValidator.php
@@ -43,22 +43,18 @@ class UnsignedIntegerValidator extends \Phramework\Validate\IntegerValidator
     protected static $type = 'unsignedinteger';
 
     /**
-     * @param int $minimum
-     * @param int|null $maximum
-     * @param int|null $exclusiveMinimum
-     * @param bool|null $exclusiveMaximum
-     * @param int $multipleOf
-     * @throws \Exception
+     * @throws \InvalidArgumentException
+     * @throws \DomainException
      */
     public function __construct(
         int $minimum = 0,
-        int $maximum = null,
+        ?int $maximum = null,
         bool $exclusiveMinimum = null,
         bool $exclusiveMaximum = null,
-        int $multipleOf = 1
+        ?int $multipleOf = 1
     ) {
         if ($minimum < 0) {
-            throw new \Exception('Minimum cannot be negative');
+            throw new \InvalidArgumentException('Minimum cannot be negative');
         }
 
         parent::__construct(
diff --git a/src/UsernameValidator.php b/src/UsernameValidator.php
index 789454d..ee3ae68 100644
--- a/src/UsernameValidator.php
+++ b/src/UsernameValidator.php
@@ -64,7 +64,7 @@ public static function getUsernamePattern() : string
      */
     public function __construct(
         int $minLength = 0,
-        int $maxLength = null
+        ?int $maxLength = null
     ) {
         parent::__construct(
             $minLength,
diff --git a/tests/src/ArrayValidatorTest.php b/tests/src/ArrayValidatorTest.php
index 359fb4e..52cf920 100644
--- a/tests/src/ArrayValidatorTest.php
+++ b/tests/src/ArrayValidatorTest.php
@@ -29,7 +29,7 @@ protected function tearDown()
     }
 
     /**
-     * @expectedException \Exception
+     * @expectedException \TypeError
      */
     public function testConstructFailure1()
     {
@@ -52,7 +52,7 @@ public function testConstructFailure3()
     }
 
     /**
-     * @expectedException \Exception
+     * @expectedException \TypeError
      */
     public function testConstructFailure4()
     {
diff --git a/tests/src/IntegerValidatorTest.php b/tests/src/IntegerValidatorTest.php
index 4a8a155..ab6ba09 100644
--- a/tests/src/IntegerValidatorTest.php
+++ b/tests/src/IntegerValidatorTest.php
@@ -9,7 +9,6 @@
  */
 class IntegerValidatorTest extends TestCase
 {
-
     /**
      * @var IntegerValidator
      */
@@ -188,4 +187,18 @@ public function testForOverflow()
 
         $this->assertSame($value, $parsed);
     }
+
+    /**
+     * @expectedException \InvalidArgumentException
+     */
+    public function testShouldFailWhenMultipleOfIsNotPositiveInteger()
+    {
+        new IntegerValidator(
+            null,
+            null,
+            null,
+            null,
+            -1
+        );
+    }
 }
diff --git a/tests/src/NumberValidatorTest.php b/tests/src/NumberValidatorTest.php
index 76a0540..064e72e 100644
--- a/tests/src/NumberValidatorTest.php
+++ b/tests/src/NumberValidatorTest.php
@@ -24,13 +24,6 @@ protected function setUp()
         $this->object = new NumberValidator(-1000, 1000, true);
     }
 
-    /**
-     * Tears down the fixture, for example, closes a network connection.
-     * This method is called after a test is executed.
-     */
-    protected function tearDown()
-    {
-    }
 
     public function validateSuccessProvider()
     {
@@ -57,7 +50,7 @@ public function validateFailureProvider()
             ['abc'],
             ['+xyz'],
             ['++30'],
-            [-1000], //should fail becaus of exclusiveMinimum
+            [-1000], //should fail because of exclusiveMinimum
             [-10000000],
             [10000000],
             ['-1000000000']
@@ -65,43 +58,7 @@ public function validateFailureProvider()
     }
 
     /**
-      * @expectedException \TypeError
-     */
-    public function testConstructFailure1()
-    {
-        $validator = new NumberValidator(
-            'a',
-            1
-        );
-    }
-    
-    /**
-     * @expectedException \Exception
-     */
-    /*public function testConstructFailure3()
-    {
-        $validator = new NumberValidator(
-            1,
-            2,
-            'a'
-        );
-    }*/
-
-    /**
-     * @expectedException \Exception
-     */
-    /*public function testConstructFailure4()
-    {
-        $validator = new NumberValidator(
-            1,
-            2,
-            true,
-            'a'
-        );
-    }*/
-
-    /**
-     * @expectedException \Exception
+     * @expectedException \DomainException
      */
     public function testConstructFailure6()
     {
@@ -162,7 +119,7 @@ private function validateSuccess(NumberValidator $object, $input, $expected)
     }
 
     /**
-          * @dataProvider validateSuccessProvider
+     * @dataProvider validateSuccessProvider
      */
     public function testValidateSuccess($input, $expected)
     {
@@ -170,7 +127,7 @@ public function testValidateSuccess($input, $expected)
     }
 
     /**
-          * @dataProvider validateSuccessProvider
+     * @dataProvider validateSuccessProvider
      */
     public function testValidateNumberSuccess($input, $expected)
     {
@@ -178,7 +135,7 @@ public function testValidateNumberSuccess($input, $expected)
     }
 
     /**
-          * @dataProvider validateFailureProvider
+     * @dataProvider validateFailureProvider
      */
     public function testValidateNumberFailure($input)
     {
@@ -225,4 +182,18 @@ public function testGetType()
     {
         $this->assertEquals('number', $this->object->getType());
     }
+
+    /**
+     * @expectedException \InvalidArgumentException
+     */
+    public function testShouldFailWhenMultipleOfIsNotPositiveNumber()
+    {
+        new NumberValidator(
+            null,
+            null,
+            null,
+            null,
+            -1
+        );
+    }
 }