diff --git a/Makefile b/Makefile
new file mode 100644
index 00000000..cc456a56
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,6 @@
+phpcs: vendor
+	vendor/bin/phpcs -s --standard=PSR12 --extensions=php bin demo src tests
+
+vendor: composer.json
+	composer update
+	touch $@
diff --git a/composer.json b/composer.json
index a9184092..59946f84 100644
--- a/composer.json
+++ b/composer.json
@@ -34,7 +34,8 @@
     "require-dev": {
         "friendsofphp/php-cs-fixer": "~2.2.20||~2.15.1",
         "json-schema/json-schema-test-suite": "1.2.0",
-        "phpunit/phpunit": "^4.8.35"
+        "phpunit/phpunit": "^4.8.35",
+        "squizlabs/php_codesniffer": "~3.5"
     },
     "extra": {
         "branch-alias": {
diff --git a/src/JsonSchema/ConstraintError.php b/src/JsonSchema/ConstraintError.php
index fd5ba8e6..18521ec8 100644
--- a/src/JsonSchema/ConstraintError.php
+++ b/src/JsonSchema/ConstraintError.php
@@ -6,57 +6,59 @@
 
 class ConstraintError extends Enum
 {
-    const ADDITIONAL_ITEMS = 'additionalItems';
-    const ADDITIONAL_PROPERTIES = 'additionalProp';
-    const ALL_OF = 'allOf';
-    const ANY_OF = 'anyOf';
-    const DEPENDENCIES = 'dependencies';
-    const DISALLOW = 'disallow';
-    const DIVISIBLE_BY = 'divisibleBy';
-    const ENUM = 'enum';
-    const CONSTANT = 'const';
-    const EXCLUSIVE_MINIMUM = 'exclusiveMinimum';
-    const EXCLUSIVE_MAXIMUM = 'exclusiveMaximum';
-    const FORMAT_COLOR = 'colorFormat';
-    const FORMAT_DATE = 'dateFormat';
-    const FORMAT_DATE_TIME = 'dateTimeFormat';
-    const FORMAT_DATE_UTC = 'dateUtcFormat';
-    const FORMAT_EMAIL = 'emailFormat';
-    const FORMAT_HOSTNAME = 'styleHostName';
-    const FORMAT_IP = 'ipFormat';
-    const FORMAT_PHONE = 'phoneFormat';
-    const FORMAT_REGEX= 'regexFormat';
-    const FORMAT_STYLE = 'styleFormat';
-    const FORMAT_TIME = 'timeFormat';
-    const FORMAT_URL = 'urlFormat';
-    const FORMAT_URL_REF = 'urlRefFormat';
-    const INVALID_SCHEMA = 'invalidSchema';
-    const LENGTH_MAX = 'maxLength';
-    const LENGTH_MIN = 'minLength';
-    const MAXIMUM = 'maximum';
-    const MIN_ITEMS = 'minItems';
-    const MINIMUM = 'minimum';
-    const MISSING_ERROR = 'missingError';
-    const MISSING_MAXIMUM = 'missingMaximum';
-    const MISSING_MINIMUM = 'missingMinimum';
-    const MAX_ITEMS = 'maxItems';
-    const MULTIPLE_OF = 'multipleOf';
-    const NOT = 'not';
-    const ONE_OF = 'oneOf';
-    const REQUIRED = 'required';
-    const REQUIRES = 'requires';
-    const PATTERN = 'pattern';
-    const PREGEX_INVALID = 'pregrex';
-    const PROPERTIES_MIN = 'minProperties';
-    const PROPERTIES_MAX = 'maxProperties';
-    const TYPE = 'type';
-    const UNIQUE_ITEMS = 'uniqueItems';
+    public const ADDITIONAL_ITEMS = 'additionalItems';
+    public const ADDITIONAL_PROPERTIES = 'additionalProp';
+    public const ALL_OF = 'allOf';
+    public const ANY_OF = 'anyOf';
+    public const DEPENDENCIES = 'dependencies';
+    public const DISALLOW = 'disallow';
+    public const DIVISIBLE_BY = 'divisibleBy';
+    public const ENUM = 'enum';
+    public const CONSTANT = 'const';
+    public const EXCLUSIVE_MINIMUM = 'exclusiveMinimum';
+    public const EXCLUSIVE_MAXIMUM = 'exclusiveMaximum';
+    public const FORMAT_COLOR = 'colorFormat';
+    public const FORMAT_DATE = 'dateFormat';
+    public const FORMAT_DATE_TIME = 'dateTimeFormat';
+    public const FORMAT_DATE_UTC = 'dateUtcFormat';
+    public const FORMAT_EMAIL = 'emailFormat';
+    public const FORMAT_HOSTNAME = 'styleHostName';
+    public const FORMAT_IP = 'ipFormat';
+    public const FORMAT_PHONE = 'phoneFormat';
+    public const FORMAT_REGEX = 'regexFormat';
+    public const FORMAT_STYLE = 'styleFormat';
+    public const FORMAT_TIME = 'timeFormat';
+    public const FORMAT_URL = 'urlFormat';
+    public const FORMAT_URL_REF = 'urlRefFormat';
+    public const INVALID_SCHEMA = 'invalidSchema';
+    public const LENGTH_MAX = 'maxLength';
+    public const LENGTH_MIN = 'minLength';
+    public const MAXIMUM = 'maximum';
+    public const MIN_ITEMS = 'minItems';
+    public const MINIMUM = 'minimum';
+    public const MISSING_ERROR = 'missingError';
+    public const MISSING_MAXIMUM = 'missingMaximum';
+    public const MISSING_MINIMUM = 'missingMinimum';
+    public const MAX_ITEMS = 'maxItems';
+    public const MULTIPLE_OF = 'multipleOf';
+    public const NOT = 'not';
+    public const ONE_OF = 'oneOf';
+    public const REQUIRED = 'required';
+    public const REQUIRES = 'requires';
+    public const PATTERN = 'pattern';
+    public const PREGEX_INVALID = 'pregrex';
+    public const PROPERTIES_MIN = 'minProperties';
+    public const PROPERTIES_MAX = 'maxProperties';
+    public const TYPE = 'type';
+    public const UNIQUE_ITEMS = 'uniqueItems';
 
     public function getMessage()
     {
         $name = $this->getValue();
         static $messages = array(
+            // phpcs:ignore Generic.Files.LineLength.TooLong
             self::ADDITIONAL_ITEMS => 'The item %s[%s] is not defined and the definition does not allow additional items',
+            // phpcs:ignore Generic.Files.LineLength.TooLong
             self::ADDITIONAL_PROPERTIES => 'The property %s is not defined and the definition does not allow additional properties',
             self::ALL_OF => 'Failed to match all schemas',
             self::ANY_OF => 'Failed to match at least one schema',
@@ -69,13 +71,14 @@ public function getMessage()
             self::EXCLUSIVE_MAXIMUM => 'Must have a maximum value less than %d',
             self::FORMAT_COLOR => 'Invalid color',
             self::FORMAT_DATE => 'Invalid date %s, expected format YYYY-MM-DD',
+            // phpcs:ignore Generic.Files.LineLength.TooLong
             self::FORMAT_DATE_TIME => 'Invalid date-time %s, expected format YYYY-MM-DDThh:mm:ssZ or YYYY-MM-DDThh:mm:ss+hh:mm',
             self::FORMAT_DATE_UTC => 'Invalid time %s, expected integer of milliseconds since Epoch',
             self::FORMAT_EMAIL => 'Invalid email',
             self::FORMAT_HOSTNAME => 'Invalid hostname',
             self::FORMAT_IP => 'Invalid IP address',
             self::FORMAT_PHONE => 'Invalid phone number',
-            self::FORMAT_REGEX=> 'Invalid regex format %s',
+            self::FORMAT_REGEX => 'Invalid regex format %s',
             self::FORMAT_STYLE => 'Invalid style',
             self::FORMAT_TIME => 'Invalid time %s, expected format hh:mm:ss',
             self::FORMAT_URL => 'Invalid URL format',
diff --git a/src/JsonSchema/Constraints/CollectionConstraint.php b/src/JsonSchema/Constraints/CollectionConstraint.php
index 825d4531..a4317de2 100644
--- a/src/JsonSchema/Constraints/CollectionConstraint.php
+++ b/src/JsonSchema/Constraints/CollectionConstraint.php
@@ -73,7 +73,11 @@ protected function validateItems(&$value, $schema = null, JsonPointer $path = nu
                 $this->checkUndefined($v, $schema->items, $path, $k);
 
                 // Recheck with "additionalItems" if the first test fails
-                if (count($initErrors) < count($this->getErrors()) && (isset($schema->additionalItems) && $schema->additionalItems !== false)) {
+                if (
+                    count($initErrors) < count($this->getErrors())
+                    && (isset($schema->additionalItems)
+                    && $schema->additionalItems !== false)
+                ) {
                     $secondErrors = $this->getErrors();
                     $this->checkUndefined($v, $schema->additionalItems, $path, $k);
                 }
diff --git a/src/JsonSchema/Constraints/Constraint.php b/src/JsonSchema/Constraints/Constraint.php
index 389e0f53..360f263c 100644
--- a/src/JsonSchema/Constraints/Constraint.php
+++ b/src/JsonSchema/Constraints/Constraint.php
@@ -21,16 +21,16 @@ abstract class Constraint extends BaseConstraint implements ConstraintInterface
 {
     protected $inlineSchemaProperty = '$schema';
 
-    const CHECK_MODE_NONE =             0x00000000;
-    const CHECK_MODE_NORMAL =           0x00000001;
-    const CHECK_MODE_TYPE_CAST =        0x00000002;
-    const CHECK_MODE_COERCE_TYPES =     0x00000004;
-    const CHECK_MODE_APPLY_DEFAULTS =   0x00000008;
-    const CHECK_MODE_EXCEPTIONS =       0x00000010;
-    const CHECK_MODE_DISABLE_FORMAT =   0x00000020;
-    const CHECK_MODE_EARLY_COERCE =     0x00000040;
-    const CHECK_MODE_ONLY_REQUIRED_DEFAULTS   = 0x00000080;
-    const CHECK_MODE_VALIDATE_SCHEMA =  0x00000100;
+    public const CHECK_MODE_NONE                   = 0x00000000;
+    public const CHECK_MODE_NORMAL                 = 0x00000001;
+    public const CHECK_MODE_TYPE_CAST              = 0x00000002;
+    public const CHECK_MODE_COERCE_TYPES           = 0x00000004;
+    public const CHECK_MODE_APPLY_DEFAULTS         = 0x00000008;
+    public const CHECK_MODE_EXCEPTIONS             = 0x00000010;
+    public const CHECK_MODE_DISABLE_FORMAT         = 0x00000020;
+    public const CHECK_MODE_EARLY_COERCE           = 0x00000040;
+    public const CHECK_MODE_ONLY_REQUIRED_DEFAULTS = 0x00000080;
+    public const CHECK_MODE_VALIDATE_SCHEMA        = 0x00000100;
 
     /**
      * Bubble down the path
@@ -79,11 +79,25 @@ protected function checkArray(&$value, $schema = null, JsonPointer $path = null,
      * @param mixed            $additionalProperties
      * @param mixed            $patternProperties
      */
-    protected function checkObject(&$value, $schema = null, JsonPointer $path = null, $properties = null,
-        $additionalProperties = null, $patternProperties = null, $appliedDefaults = array())
-    {
+    protected function checkObject(
+        &$value,
+        $schema = null,
+        JsonPointer $path = null,
+        $properties = null,
+        $additionalProperties = null,
+        $patternProperties = null,
+        $appliedDefaults = array()
+    ) {
         $validator = $this->factory->createInstanceFor('object');
-        $validator->check($value, $schema, $path, $properties, $additionalProperties, $patternProperties, $appliedDefaults);
+        $validator->check(
+            $value,
+            $schema,
+            $path,
+            $properties,
+            $additionalProperties,
+            $patternProperties,
+            $appliedDefaults
+        );
 
         $this->addErrors($validator->getErrors());
     }
@@ -112,11 +126,22 @@ protected function checkType(&$value, $schema = null, JsonPointer $path = null,
      * @param JsonPointer|null $path
      * @param mixed            $i
      */
-    protected function checkUndefined(&$value, $schema = null, JsonPointer $path = null, $i = null, $fromDefault = false)
-    {
+    protected function checkUndefined(
+        &$value,
+        $schema = null,
+        JsonPointer $path = null,
+        $i = null,
+        $fromDefault = false
+    ) {
         $validator = $this->factory->createInstanceFor('undefined');
 
-        $validator->check($value, $this->factory->getSchemaStorage()->resolveRefSchema($schema), $path, $i, $fromDefault);
+        $validator->check(
+            $value,
+            $this->factory->getSchemaStorage()->resolveRefSchema($schema),
+            $path,
+            $i,
+            $fromDefault
+        );
 
         $this->addErrors($validator->getErrors());
     }
diff --git a/src/JsonSchema/Constraints/FormatConstraint.php b/src/JsonSchema/Constraints/FormatConstraint.php
index a55356d1..19027822 100644
--- a/src/JsonSchema/Constraints/FormatConstraint.php
+++ b/src/JsonSchema/Constraints/FormatConstraint.php
@@ -34,7 +34,10 @@ public function check(&$element, $schema = null, JsonPointer $path = null, $i =
         switch ($schema->format) {
             case 'date':
                 if (!$date = $this->validateDateTime($element, 'Y-m-d')) {
-                    $this->addError(ConstraintError::FORMAT_DATE(), $path, array(
+                    $this->addError(
+                        ConstraintError::FORMAT_DATE(),
+                        $path,
+                        array(
                             'date' => $element,
                             'format' => $schema->format
                         )
@@ -44,7 +47,10 @@ public function check(&$element, $schema = null, JsonPointer $path = null, $i =
 
             case 'time':
                 if (!$this->validateDateTime($element, 'H:i:s')) {
-                    $this->addError(ConstraintError::FORMAT_TIME(), $path, array(
+                    $this->addError(
+                        ConstraintError::FORMAT_TIME(),
+                        $path,
+                        array(
                             'time' => json_encode($element),
                             'format' => $schema->format,
                         )
@@ -54,7 +60,10 @@ public function check(&$element, $schema = null, JsonPointer $path = null, $i =
 
             case 'date-time':
                 if (null === Rfc3339::createFromString($element)) {
-                    $this->addError(ConstraintError::FORMAT_DATE_TIME(), $path, array(
+                    $this->addError(
+                        ConstraintError::FORMAT_DATE_TIME(),
+                        $path,
+                        array(
                             'dateTime' => json_encode($element),
                             'format' => $schema->format
                         )
@@ -72,7 +81,10 @@ public function check(&$element, $schema = null, JsonPointer $path = null, $i =
 
             case 'regex':
                 if (!$this->validateRegex($element)) {
-                    $this->addError(ConstraintError::FORMAT_REGEX(), $path, array(
+                    $this->addError(
+                        ConstraintError::FORMAT_REGEX(),
+                        $path,
+                        array(
                             'value' => $element,
                             'format' => $schema->format
                         )
@@ -119,7 +131,11 @@ public function check(&$element, $schema = null, JsonPointer $path = null, $i =
                         if (strpos($pathParts[0], ':') !== false) {
                             $validURL = null;
                         } else {
-                            $validURL = filter_var('scheme://host/' . $element, FILTER_VALIDATE_URL, FILTER_NULL_ON_FAILURE);
+                            $validURL = filter_var(
+                                'scheme://host/' . $element,
+                                FILTER_VALIDATE_URL,
+                                FILTER_NULL_ON_FAILURE
+                            );
                         }
                     } else {
                         $validURL = null;
@@ -202,9 +218,11 @@ protected function validateRegex($regex)
 
     protected function validateColor($color)
     {
-        if (in_array(strtolower($color), array('aqua', 'black', 'blue', 'fuchsia',
+        if (
+            in_array(strtolower($color), array('aqua', 'black', 'blue', 'fuchsia',
             'gray', 'green', 'lime', 'maroon', 'navy', 'olive', 'orange', 'purple',
-            'red', 'silver', 'teal', 'white', 'yellow'))) {
+            'red', 'silver', 'teal', 'white', 'yellow'))
+        ) {
             return true;
         }
 
@@ -226,6 +244,7 @@ protected function validatePhone($phone)
 
     protected function validateHostname($host)
     {
+        // phpcs:ignore Generic.Files.LineLength.TooLong
         $hostnameRegex = '/^(([a-zA-Z0-9]|[a-zA-Z0-9][a-zA-Z0-9\-]*[a-zA-Z0-9])\.)*([A-Za-z0-9]|[A-Za-z0-9][A-Za-z0-9\-]*[A-Za-z0-9])$/i';
 
         return preg_match($hostnameRegex, $host);
diff --git a/src/JsonSchema/Constraints/ObjectConstraint.php b/src/JsonSchema/Constraints/ObjectConstraint.php
index dd1c02b9..ef6e2fcf 100644
--- a/src/JsonSchema/Constraints/ObjectConstraint.php
+++ b/src/JsonSchema/Constraints/ObjectConstraint.php
@@ -28,9 +28,15 @@ class ObjectConstraint extends Constraint
     /**
      * {@inheritdoc}
      */
-    public function check(&$element, $schema = null, JsonPointer $path = null, $properties = null,
-        $additionalProp = null, $patternProperties = null, $appliedDefaults = array())
-    {
+    public function check(
+        &$element,
+        $schema = null,
+        JsonPointer $path = null,
+        $properties = null,
+        $additionalProp = null,
+        $patternProperties = null,
+        $appliedDefaults = array()
+    ) {
         if ($element instanceof UndefinedConstraint) {
             return;
         }
@@ -73,7 +79,13 @@ public function validatePatternProperties($element, JsonPointer $path = null, $p
             foreach ($element as $i => $value) {
                 if (preg_match($delimiter . $pregex . $delimiter . 'u', $i)) {
                     $matches[] = $i;
-                    $this->checkUndefined($value, $schema ?: new \stdClass(), $path, $i, in_array($i, $this->appliedDefaults));
+                    $this->checkUndefined(
+                        $value,
+                        $schema ?: new \stdClass(),
+                        $path,
+                        $i,
+                        in_array($i, $this->appliedDefaults)
+                    );
                 }
             }
         }
@@ -91,16 +103,26 @@ public function validatePatternProperties($element, JsonPointer $path = null, $p
      * @param \StdClass        $properties     Properties
      * @param mixed            $additionalProp Additional properties
      */
-    public function validateElement($element, $matches, $schema = null, JsonPointer $path = null,
-        $properties = null, $additionalProp = null)
-    {
+    public function validateElement(
+        $element,
+        $matches,
+        $schema = null,
+        JsonPointer $path = null,
+        $properties = null,
+        $additionalProp = null
+    ) {
         $this->validateMinMaxConstraint($element, $schema, $path);
 
         foreach ($element as $i => $value) {
             $definition = $this->getProperty($properties, $i);
 
             // no additional properties allowed
-            if (!in_array($i, $matches) && $additionalProp === false && $this->inlineSchemaProperty !== $i && !$definition) {
+            if (
+                !in_array($i, $matches)
+                && $additionalProp === false
+                && $this->inlineSchemaProperty !== $i
+                && !$definition
+            ) {
                 $this->addError(ConstraintError::ADDITIONAL_PROPERTIES(), $path, array('property' => $i));
             }
 
@@ -124,7 +146,11 @@ public function validateElement($element, $matches, $schema = null, JsonPointer
 
             $property = $this->getProperty($element, $i, $this->factory->createInstanceFor('undefined'));
             if (is_object($property)) {
-                $this->validateMinMaxConstraint(!($property instanceof UndefinedConstraint) ? $property : $element, $definition, $path);
+                $this->validateMinMaxConstraint(
+                    !($property instanceof UndefinedConstraint) ? $property : $element,
+                    $definition,
+                    $path
+                );
             }
         }
     }
@@ -162,7 +188,12 @@ public function validateProperties(&$element, $properties = null, JsonPointer $p
      */
     protected function &getProperty(&$element, $property, $fallback = null)
     {
-        if (is_array($element) && (isset($element[$property]) || array_key_exists($property, $element)) /*$this->checkMode == self::CHECK_MODE_TYPE_CAST*/) {
+        if (
+            is_array($element)
+            && (isset($element[$property])
+            || array_key_exists($property, $element))
+            /*$this->checkMode == self::CHECK_MODE_TYPE_CAST*/
+        ) {
             return $element[$property];
         } elseif (is_object($element) && property_exists($element, $property)) {
             return $element->$property;
@@ -183,13 +214,21 @@ protected function validateMinMaxConstraint($element, $objectDefinition, JsonPoi
         // Verify minimum number of properties
         if (isset($objectDefinition->minProperties) && !is_object($objectDefinition->minProperties)) {
             if ($this->getTypeCheck()->propertyCount($element) < $objectDefinition->minProperties) {
-                $this->addError(ConstraintError::PROPERTIES_MIN(), $path, array('minProperties' => $objectDefinition->minProperties));
+                $this->addError(
+                    ConstraintError::PROPERTIES_MIN(),
+                    $path,
+                    array('minProperties' => $objectDefinition->minProperties)
+                );
             }
         }
         // Verify maximum number of properties
         if (isset($objectDefinition->maxProperties) && !is_object($objectDefinition->maxProperties)) {
             if ($this->getTypeCheck()->propertyCount($element) > $objectDefinition->maxProperties) {
-                $this->addError(ConstraintError::PROPERTIES_MAX(), $path, array('maxProperties' => $objectDefinition->maxProperties));
+                $this->addError(
+                    ConstraintError::PROPERTIES_MAX(),
+                    $path,
+                    array('maxProperties' => $objectDefinition->maxProperties)
+                );
             }
         }
     }
diff --git a/src/JsonSchema/Constraints/SchemaConstraint.php b/src/JsonSchema/Constraints/SchemaConstraint.php
index 425c38f2..804a576e 100644
--- a/src/JsonSchema/Constraints/SchemaConstraint.php
+++ b/src/JsonSchema/Constraints/SchemaConstraint.php
@@ -24,7 +24,7 @@
  */
 class SchemaConstraint extends Constraint
 {
-    const DEFAULT_SCHEMA_SPEC = 'http://json-schema.org/draft-04/schema#';
+    private const DEFAULT_SCHEMA_SPEC = 'http://json-schema.org/draft-04/schema#';
 
     /**
      * {@inheritdoc}
diff --git a/src/JsonSchema/Constraints/TypeConstraint.php b/src/JsonSchema/Constraints/TypeConstraint.php
index ff4eba71..342c0d83 100644
--- a/src/JsonSchema/Constraints/TypeConstraint.php
+++ b/src/JsonSchema/Constraints/TypeConstraint.php
@@ -155,7 +155,8 @@ protected function validateTypeNameWording($type)
                 sprintf(
                     'No wording for %s available, expected wordings are: [%s]',
                     var_export($type, true),
-                    implode(', ', array_filter(self::$wording)))
+                    implode(', ', array_filter(self::$wording))
+                )
             );
         }
     }
@@ -233,7 +234,9 @@ protected function validateType(&$value, $type, $coerce = false)
             return is_null($value);
         }
 
-        throw new InvalidArgumentException((is_object($value) ? 'object' : $value) . ' is an invalid type for ' . $type);
+        throw new InvalidArgumentException(
+            (is_object($value) ? 'object' : $value) . ' is an invalid type for ' . $type
+        );
     }
 
     /**
diff --git a/src/JsonSchema/Constraints/UndefinedConstraint.php b/src/JsonSchema/Constraints/UndefinedConstraint.php
index bdb95f4a..19461778 100644
--- a/src/JsonSchema/Constraints/UndefinedConstraint.php
+++ b/src/JsonSchema/Constraints/UndefinedConstraint.php
@@ -140,7 +140,8 @@ protected function validateCommonProperties(&$value, $schema, JsonPointer $path,
                     if (!$this->getTypeCheck()->propertyExists($value, $required)) {
                         $this->addError(
                             ConstraintError::REQUIRED(),
-                            $this->incrementPath($path ?: new JsonPointer(''), $required), array(
+                            $this->incrementPath($path ?: new JsonPointer(''), $required),
+                            array(
                                 'property' => $required
                             )
                         );
@@ -280,7 +281,8 @@ protected function applyDefaultValues(&$value, $schema, $path)
                 if (
                     !array_key_exists($currentItem, $value)
                     && property_exists($itemDefinition, 'default')
-                    && $this->shouldApplyDefaultValue($requiredOnly, $itemDefinition)) {
+                    && $this->shouldApplyDefaultValue($requiredOnly, $itemDefinition)
+                ) {
                     if (is_object($itemDefinition->default)) {
                         $value[$currentItem] = clone $itemDefinition->default;
                     } else {
@@ -292,7 +294,8 @@ protected function applyDefaultValues(&$value, $schema, $path)
         } elseif (
             $value instanceof self
             && property_exists($schema, 'default')
-            && $this->shouldApplyDefaultValue($requiredOnly, $schema)) {
+            && $this->shouldApplyDefaultValue($requiredOnly, $schema)
+        ) {
             // $value is a leaf, not a container - apply the default directly
             $value = is_object($schema->default) ? clone $schema->default : $schema->default;
             $path->setFromDefault();
diff --git a/src/JsonSchema/Rfc3339.php b/src/JsonSchema/Rfc3339.php
index adca581a..8c2c4708 100644
--- a/src/JsonSchema/Rfc3339.php
+++ b/src/JsonSchema/Rfc3339.php
@@ -4,7 +4,7 @@
 
 class Rfc3339
 {
-    const REGEX = '/^(\d{4}-\d{2}-\d{2}[T ]{1}\d{2}:\d{2}:\d{2})(\.\d+)?(Z|([+-]\d{2}):?(\d{2}))$/';
+    private const REGEX = '/^(\d{4}-\d{2}-\d{2}[T ]{1}\d{2}:\d{2}:\d{2})(\.\d+)?(Z|([+-]\d{2}):?(\d{2}))$/';
 
     /**
      * Try creating a DateTime instance
@@ -23,7 +23,11 @@ public static function createFromString($string)
         $microseconds = $matches[2] ?: '.000000';
         $timeZone = 'Z' !== $matches[3] ? $matches[4] . ':' . $matches[5] : '+00:00';
         $dateFormat = strpos($dateAndTime, 'T') === false ? 'Y-m-d H:i:s.uP' : 'Y-m-d\TH:i:s.uP';
-        $dateTime = \DateTime::createFromFormat($dateFormat, $dateAndTime . $microseconds . $timeZone, new \DateTimeZone('UTC'));
+        $dateTime = \DateTime::createFromFormat(
+            $dateFormat,
+            $dateAndTime . $microseconds . $timeZone,
+            new \DateTimeZone('UTC')
+        );
 
         return $dateTime ?: null;
     }
diff --git a/src/JsonSchema/SchemaStorage.php b/src/JsonSchema/SchemaStorage.php
index 81b3508c..660b05a4 100644
--- a/src/JsonSchema/SchemaStorage.php
+++ b/src/JsonSchema/SchemaStorage.php
@@ -10,7 +10,7 @@
 
 class SchemaStorage implements SchemaStorageInterface
 {
-    const INTERNAL_PROVIDED_SCHEMA_URI = 'internal://provided-schema/';
+    public const INTERNAL_PROVIDED_SCHEMA_URI = 'internal://provided-schema/';
 
     protected $uriRetriever;
     protected $uriResolver;
diff --git a/src/JsonSchema/Uri/Retrievers/AbstractRetriever.php b/src/JsonSchema/Uri/Retrievers/AbstractRetriever.php
index 9ab24b95..84220305 100644
--- a/src/JsonSchema/Uri/Retrievers/AbstractRetriever.php
+++ b/src/JsonSchema/Uri/Retrievers/AbstractRetriever.php
@@ -1,4 +1,5 @@
 <?php
+
 /**
  * JsonSchema
  *
diff --git a/src/JsonSchema/Uri/Retrievers/FileGetContents.php b/src/JsonSchema/Uri/Retrievers/FileGetContents.php
index 7019814f..27f6cf5e 100644
--- a/src/JsonSchema/Uri/Retrievers/FileGetContents.php
+++ b/src/JsonSchema/Uri/Retrievers/FileGetContents.php
@@ -42,7 +42,8 @@ public function retrieve($uri)
             throw new ResourceNotFoundException('JSON schema not found at ' . $uri);
         }
 
-        if ($response == ''
+        if (
+            $response == ''
             && substr($uri, 0, 7) == 'file://' && substr($uri, -1) == '/'
         ) {
             throw new ResourceNotFoundException('JSON schema not found at ' . $uri);
diff --git a/src/JsonSchema/Uri/UriResolver.php b/src/JsonSchema/Uri/UriResolver.php
index 8ab6650e..80d47661 100644
--- a/src/JsonSchema/Uri/UriResolver.php
+++ b/src/JsonSchema/Uri/UriResolver.php
@@ -135,9 +135,11 @@ public static function combineRelativePathWithBasePath($relativePath, $basePath)
         $basePathSegments = explode('/', $basePath);
 
         preg_match('|^/?(\.\./(?:\./)*)*|', $relativePath, $match);
-        $numLevelUp = strlen($match[0]) /3 + 1;
+        $numLevelUp = strlen($match[0]) / 3 + 1;
         if ($numLevelUp >= count($basePathSegments)) {
-            throw new UriResolverException(sprintf("Unable to resolve URI '%s' from base '%s'", $relativePath, $basePath));
+            throw new UriResolverException(
+                sprintf("Unable to resolve URI '%s' from base '%s'", $relativePath, $basePath)
+            );
         }
 
         $basePathSegments = array_slice($basePathSegments, 0, -$numLevelUp);
diff --git a/src/JsonSchema/Validator.php b/src/JsonSchema/Validator.php
index 7b31279c..17dff577 100644
--- a/src/JsonSchema/Validator.php
+++ b/src/JsonSchema/Validator.php
@@ -22,12 +22,12 @@
  */
 class Validator extends BaseConstraint
 {
-    const SCHEMA_MEDIA_TYPE = 'application/schema+json';
+    public const SCHEMA_MEDIA_TYPE = 'application/schema+json';
 
-    const ERROR_NONE                    = 0x00000000;
-    const ERROR_ALL                     = 0xFFFFFFFF;
-    const ERROR_DOCUMENT_VALIDATION     = 0x00000001;
-    const ERROR_SCHEMA_VALIDATION       = 0x00000002;
+    public const ERROR_NONE                = 0x00000000;
+    public const ERROR_ALL                 = 0xFFFFFFFF;
+    public const ERROR_DOCUMENT_VALIDATION = 0x00000001;
+    public const ERROR_SCHEMA_VALIDATION   = 0x00000002;
 
     /**
      * Validates the given data against the schema and returns an object containing the results
diff --git a/tests/Constraints/AdditionalPropertiesTest.php b/tests/Constraints/AdditionalPropertiesTest.php
index e064312d..be8fb64f 100644
--- a/tests/Constraints/AdditionalPropertiesTest.php
+++ b/tests/Constraints/AdditionalPropertiesTest.php
@@ -39,6 +39,7 @@ public function getInvalidTests()
                     array(
                         'property'   => '',
                         'pointer'    => '',
+                        // phpcs:ignore Generic.Files.LineLength.TooLong
                         'message'    => 'The property additionalProp is not defined and the definition does not allow additional properties',
                         'constraint' => array(
                             'name' => 'additionalProp',
diff --git a/tests/Constraints/BaseTestCase.php b/tests/Constraints/BaseTestCase.php
index 50efbd82..04d3a739 100644
--- a/tests/Constraints/BaseTestCase.php
+++ b/tests/Constraints/BaseTestCase.php
@@ -55,6 +55,7 @@ public function testInvalidCases($input, $schema, $checkMode = Constraint::CHECK
     /**
      * @dataProvider getInvalidForAssocTests
      */
+    // phpcs:ignore Generic.Files.LineLength.TooLong
     public function testInvalidCasesUsingAssoc($input, $schema, $checkMode = Constraint::CHECK_MODE_TYPE_CAST, $errors = array())
     {
         $checkMode = $checkMode === null ? Constraint::CHECK_MODE_TYPE_CAST : $checkMode;
diff --git a/tests/Constraints/CoerciveTest.php b/tests/Constraints/CoerciveTest.php
index 22684b3e..e484df5c 100644
--- a/tests/Constraints/CoerciveTest.php
+++ b/tests/Constraints/CoerciveTest.php
@@ -39,7 +39,7 @@ public function dataCoerceCases()
                 array('array',      '[45]',         '45',           true),  // #5
                 array('object',     '{"a":"b"}',    null,           false), // #6
                 array('array',      '[{"a":"b"}]',  null,           false), // #7
-                array('array',      '[1,2]',  		array(1, 2),     false), // #8
+                array('array',      '[1,2]',        array(1, 2),    false), // #8
             ),
             'integer' => array(
                 array('string',     '"45"',         45,             true),  // #9
@@ -190,6 +190,7 @@ public function dataCoerceCases()
     }
 
     /** @dataProvider dataCoerceCases **/
+    // phpcs:ignore Generic.Files.LineLength.TooLong
     public function testCoerceCases($schema, $data, $startType, $endType, $endValue, $valid, $extraFlags = 0, $assoc = false)
     {
         $validator = new Validator($this->factory);
diff --git a/tests/Constraints/FactoryTest.php b/tests/Constraints/FactoryTest.php
index adc11844..f002578a 100644
--- a/tests/Constraints/FactoryTest.php
+++ b/tests/Constraints/FactoryTest.php
@@ -28,6 +28,7 @@ class MyBadConstraint
  *
  * @package JsonSchema\Tests\Constraints
  */
+// phpcs:ignore PSR1.Classes.ClassDeclaration.MultipleClasses
 class MyStringConstraint extends Constraint
 {
     public function check(&$value, $schema = null, JsonPointer $path = null, $i = null)
@@ -35,6 +36,7 @@ public function check(&$value, $schema = null, JsonPointer $path = null, $i = nu
     }
 }
 
+// phpcs:ignore PSR1.Classes.ClassDeclaration.MultipleClasses
 class FactoryTest extends TestCase
 {
     /**
diff --git a/tests/Constraints/OfPropertiesTest.php b/tests/Constraints/OfPropertiesTest.php
index ff8bded3..7c15da8a 100644
--- a/tests/Constraints/OfPropertiesTest.php
+++ b/tests/Constraints/OfPropertiesTest.php
@@ -1,4 +1,5 @@
 <?php
+
 /*
  * This file is part of the JsonSchema package.
  *
diff --git a/tests/Constraints/TypeTest.php b/tests/Constraints/TypeTest.php
index ca6bf7cf..cbd17451 100644
--- a/tests/Constraints/TypeTest.php
+++ b/tests/Constraints/TypeTest.php
@@ -76,15 +76,18 @@ private function assertTypeConstraintError($expected, TypeConstraint $actual)
     {
         $actualErrors = $actual->getErrors();
 
+        // phpcs:ignore Generic.Files.LineLength.TooLong
         $this->assertCount(1, $actualErrors, 'Failed to assert that Type has exactly one error to assert the error message against.');
 
         $actualError = $actualErrors[0];
 
+        // phpcs:ignore Generic.Files.LineLength.TooLong
         $this->assertInternalType('array', $actualError, sprintf('Failed to assert that Type error is an array, %s given', gettype($actualError)));
 
         $messageKey = 'message';
         $this->assertArrayHasKey(
-            $messageKey, $actualError,
+            $messageKey,
+            $actualError,
             sprintf('Failed to assert that Type error has a message key %s.', var_export($messageKey, true))
         );
 
@@ -103,6 +106,7 @@ public function testValidateTypeNameWording()
 
         $this->setExpectedException(
             '\UnexpectedValueException',
+            // phpcs:ignore Generic.Files.LineLength.TooLong
             "No wording for 'notAValidTypeName' available, expected wordings are: [an integer, a number, a boolean, an object, an array, a string, a null]"
         );
         $m->invoke($t, 'notAValidTypeName');
diff --git a/tests/Iterators/ObjectIteratorTest.php b/tests/Iterators/ObjectIteratorTest.php
index e36d2ea4..359796c6 100644
--- a/tests/Iterators/ObjectIteratorTest.php
+++ b/tests/Iterators/ObjectIteratorTest.php
@@ -69,7 +69,7 @@ public function testKey()
 
     public function testAlwaysObjects()
     {
-        $i= new ObjectIterator($this->testObject);
+        $i = new ObjectIterator($this->testObject);
 
         foreach ($i as $item) {
             $this->assertInstanceOf('\StdClass', $item);
diff --git a/tests/Rfc3339Test.php b/tests/Rfc3339Test.php
index e489d389..53a8988c 100644
--- a/tests/Rfc3339Test.php
+++ b/tests/Rfc3339Test.php
@@ -26,7 +26,10 @@ public function testCreateFromValidString($string, \DateTime $expected)
      */
     public function testCreateFromInvalidString($string)
     {
-        $this->assertNull(Rfc3339::createFromString($string), sprintf('String "%s" should not be converted to DateTime', $string));
+        $this->assertNull(
+            Rfc3339::createFromString($string),
+            sprintf('String "%s" should not be converted to DateTime', $string)
+        );
     }
 
     public function provideValidFormats()
diff --git a/tests/SchemaStorageTest.php b/tests/SchemaStorageTest.php
index ebbc9477..ee4b271f 100644
--- a/tests/SchemaStorageTest.php
+++ b/tests/SchemaStorageTest.php
@@ -181,10 +181,10 @@ private function getMainSchema()
                     )
                 ),
                 'yardproperties' => (object) array(
-                    'tree'=>(object) array(
+                    'tree' => (object) array(
                         'type' => 'string'
                     ),
-                    'pool'=>(object) array(
+                    'pool' => (object) array(
                         'type' => 'string'
                     )
                 )
diff --git a/tests/Uri/Retrievers/FileGetContentsTest.php b/tests/Uri/Retrievers/FileGetContentsTest.php
index 0514a7d5..f727541f 100644
--- a/tests/Uri/Retrievers/FileGetContentsTest.php
+++ b/tests/Uri/Retrievers/FileGetContentsTest.php
@@ -67,9 +67,12 @@ public function testContentType()
     function file_get_contents($uri)
     {
         switch ($uri) {
-            case 'http://example.com/false': return false;
-            case 'file:///this/is/a/directory/': return '';
-            default: return \file_get_contents($uri);
+            case 'http://example.com/false':
+                return false;
+            case 'file:///this/is/a/directory/':
+                return '';
+            default:
+                return \file_get_contents($uri);
         }
     }
 }
diff --git a/tests/Uri/UriRetrieverTest.php b/tests/Uri/UriRetrieverTest.php
index 24714a26..4ca8b7bb 100644
--- a/tests/Uri/UriRetrieverTest.php
+++ b/tests/Uri/UriRetrieverTest.php
@@ -157,7 +157,8 @@ public function testResolvePointerNoFragment()
         $this->assertEquals(
             $schema,
             $retriever->resolvePointer(
-                $schema, 'http://example.org/schema.json'
+                $schema,
+                'http://example.org/schema.json'
             )
         );
     }
@@ -177,7 +178,8 @@ public function testResolvePointerFragment()
         $this->assertEquals(
             $schema->definitions->foo,
             $retriever->resolvePointer(
-                $schema, 'http://example.org/schema.json#/definitions/foo'
+                $schema,
+                'http://example.org/schema.json#/definitions/foo'
             )
         );
     }
@@ -198,7 +200,8 @@ public function testResolvePointerFragmentNotFound()
 
         $retriever = new \JsonSchema\Uri\UriRetriever();
         $retriever->resolvePointer(
-            $schema, 'http://example.org/schema.json#/definitions/bar'
+            $schema,
+            'http://example.org/schema.json#/definitions/bar'
         );
     }
 
@@ -218,7 +221,8 @@ public function testResolvePointerFragmentNoArray()
 
         $retriever = new \JsonSchema\Uri\UriRetriever();
         $retriever->resolvePointer(
-            $schema, 'http://example.org/schema.json#/definitions/foo'
+            $schema,
+            'http://example.org/schema.json#/definitions/foo'
         );
     }
 
@@ -229,7 +233,8 @@ public function testResolveExcessLevelUp()
     {
         $retriever = new \JsonSchema\Uri\UriRetriever();
         $retriever->resolve(
-            '../schema.json#', 'http://example.org/schema.json#'
+            '../schema.json#',
+            'http://example.org/schema.json#'
         );
     }