diff --git a/composer.json b/composer.json
index f1f6faea..3e26b0f4 100644
--- a/composer.json
+++ b/composer.json
@@ -42,7 +42,7 @@
         "json-schema/JSON-Schema-Test-Suite": "1.2.0",
         "phpunit/phpunit": "^4.8.22",
         "friendsofphp/php-cs-fixer": "^2.1",
-        "phpdocumentor/phpdocumentor": "~2"
+        "phpdocumentor/phpdocumentor": "^2.7"
     },
     "autoload": {
         "psr-4": { "JsonSchema\\": "src/JsonSchema/" }
diff --git a/src/JsonSchema/Constraints/BaseConstraint.php b/src/JsonSchema/Constraints/BaseConstraint.php
index eefb08ed..63968213 100644
--- a/src/JsonSchema/Constraints/BaseConstraint.php
+++ b/src/JsonSchema/Constraints/BaseConstraint.php
@@ -137,12 +137,12 @@ public static function arrayToObjectRecursive($array)
         $json = json_encode($array);
         if (json_last_error() !== \JSON_ERROR_NONE) {
             $message = 'Unable to encode schema array as JSON';
-            if (version_compare(phpversion(), '5.5.0', '>=')) {
+            if (function_exists('json_last_error_msg')) {
                 $message .= ': ' . json_last_error_msg();
             }
             throw new InvalidArgumentException($message);
         }
 
-        return json_decode($json);
+        return (object) json_decode($json);
     }
 }
diff --git a/src/JsonSchema/Constraints/Constraint.php b/src/JsonSchema/Constraints/Constraint.php
index b7f3bb42..e50c7d0b 100644
--- a/src/JsonSchema/Constraints/Constraint.php
+++ b/src/JsonSchema/Constraints/Constraint.php
@@ -77,13 +77,15 @@ protected function checkArray(&$value, $schema = null, JsonPointer $path = null,
      * @param mixed            $value
      * @param mixed            $schema
      * @param JsonPointer|null $path
-     * @param mixed            $i
+     * @param mixed            $properties
+     * @param mixed            $additionalProperties
      * @param mixed            $patternProperties
      */
-    protected function checkObject(&$value, $schema = null, JsonPointer $path = null, $i = 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, $i, $patternProperties, $appliedDefaults);
+        $validator->check($value, $schema, $path, $properties, $additionalProperties, $patternProperties, $appliedDefaults);
 
         $this->addErrors($validator->getErrors());
     }
diff --git a/src/JsonSchema/Constraints/FormatConstraint.php b/src/JsonSchema/Constraints/FormatConstraint.php
index c172847f..578cdb14 100644
--- a/src/JsonSchema/Constraints/FormatConstraint.php
+++ b/src/JsonSchema/Constraints/FormatConstraint.php
@@ -80,6 +80,13 @@ public function check(&$element, $schema = null, JsonPointer $path = null, $i =
                 break;
 
             case 'uri':
+                if (null === filter_var($element, FILTER_VALIDATE_URL, FILTER_NULL_ON_FAILURE)) {
+                    $this->addError($path, 'Invalid URL format', 'format', array('format' => $schema->format));
+                }
+                break;
+
+            case 'uriref':
+            case 'uri-reference':
                 if (null === filter_var($element, FILTER_VALIDATE_URL, FILTER_NULL_ON_FAILURE)) {
                     // FILTER_VALIDATE_URL does not conform to RFC-3986, and cannot handle relative URLs, but
                     // the json-schema spec uses RFC-3986, so need a bit of hackery to properly validate them.
diff --git a/src/JsonSchema/Constraints/ObjectConstraint.php b/src/JsonSchema/Constraints/ObjectConstraint.php
index 0b9a7da3..0010d294 100644
--- a/src/JsonSchema/Constraints/ObjectConstraint.php
+++ b/src/JsonSchema/Constraints/ObjectConstraint.php
@@ -27,7 +27,8 @@ class ObjectConstraint extends Constraint
     /**
      * {@inheritdoc}
      */
-    public function check(&$element, $definition = null, JsonPointer $path = 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;
@@ -37,16 +38,17 @@ public function check(&$element, $definition = null, JsonPointer $path = null, $
 
         $matches = array();
         if ($patternProperties) {
+            // validate the element pattern properties
             $matches = $this->validatePatternProperties($element, $path, $patternProperties);
         }
 
-        if ($definition) {
-            // validate the definition properties
-            $this->validateDefinition($element, $definition, $path);
+        if ($properties) {
+            // validate the element properties
+            $this->validateProperties($element, $properties, $path);
         }
 
-        // additional the element properties
-        $this->validateElement($element, $matches, $definition, $path, $additionalProp);
+        // validate additional element properties & constraints
+        $this->validateElement($element, $matches, $schema, $path, $properties, $additionalProp);
     }
 
     public function validatePatternProperties($element, JsonPointer $path = null, $patternProperties)
@@ -81,18 +83,20 @@ public function validatePatternProperties($element, JsonPointer $path = null, $p
     /**
      * Validates the element properties
      *
-     * @param \stdClass        $element          Element to validate
-     * @param array            $matches          Matches from patternProperties (if any)
-     * @param \stdClass        $objectDefinition ObjectConstraint definition
-     * @param JsonPointer|null $path             Path to test?
-     * @param mixed            $additionalProp   Additional properties
+     * @param \StdClass        $element        Element to validate
+     * @param array            $matches        Matches from patternProperties (if any)
+     * @param \StdClass        $schema         ObjectConstraint definition
+     * @param JsonPointer|null $path           Current test path
+     * @param \StdClass        $properties     Properties
+     * @param mixed            $additionalProp Additional properties
      */
-    public function validateElement($element, $matches, $objectDefinition = null, JsonPointer $path = null, $additionalProp = null)
+    public function validateElement($element, $matches, $schema = null, JsonPointer $path = null,
+        $properties = null, $additionalProp = null)
     {
-        $this->validateMinMaxConstraint($element, $objectDefinition, $path);
+        $this->validateMinMaxConstraint($element, $schema, $path);
 
         foreach ($element as $i => $value) {
-            $definition = $this->getProperty($objectDefinition, $i);
+            $definition = $this->getProperty($properties, $i);
 
             // no additional properties allowed
             if (!in_array($i, $matches) && $additionalProp === false && $this->inlineSchemaProperty !== $i && !$definition) {
@@ -124,17 +128,17 @@ public function validateElement($element, $matches, $objectDefinition = null, Js
     /**
      * Validates the definition properties
      *
-     * @param \stdClass        $element          Element to validate
-     * @param \stdClass        $objectDefinition ObjectConstraint definition
-     * @param JsonPointer|null $path             Path?
+     * @param \stdClass        $element    Element to validate
+     * @param \stdClass        $properties Property definitions
+     * @param JsonPointer|null $path       Path?
      */
-    public function validateDefinition(&$element, $objectDefinition = null, JsonPointer $path = null)
+    public function validateProperties(&$element, $properties = null, JsonPointer $path = null)
     {
         $undefinedConstraint = $this->factory->createInstanceFor('undefined');
 
-        foreach ($objectDefinition as $i => $value) {
+        foreach ($properties as $i => $value) {
             $property = &$this->getProperty($element, $i, $undefinedConstraint);
-            $definition = $this->getProperty($objectDefinition, $i);
+            $definition = $this->getProperty($properties, $i);
 
             if (is_object($definition)) {
                 // Undefined constraint will check for is_object() and quit if is not - so why pass it?
diff --git a/src/JsonSchema/Constraints/SchemaConstraint.php b/src/JsonSchema/Constraints/SchemaConstraint.php
index 6b4fefde..eed53956 100644
--- a/src/JsonSchema/Constraints/SchemaConstraint.php
+++ b/src/JsonSchema/Constraints/SchemaConstraint.php
@@ -35,16 +35,17 @@ public function check(&$element, $schema = null, JsonPointer $path = null, $i =
             // passed schema
             $validationSchema = $schema;
         } elseif ($this->getTypeCheck()->propertyExists($element, $this->inlineSchemaProperty)) {
-            $inlineSchema = $this->getTypeCheck()->propertyGet($element, $this->inlineSchemaProperty);
-            if (is_array($inlineSchema)) {
-                $inlineSchema = json_decode(json_encode($inlineSchema));
-            }
             // inline schema
-            $validationSchema = $inlineSchema;
+            $validationSchema = $this->getTypeCheck()->propertyGet($element, $this->inlineSchemaProperty);
         } else {
             throw new InvalidArgumentException('no schema found to verify against');
         }
 
+        // cast array schemas to object
+        if (is_array($validationSchema)) {
+            $validationSchema = BaseConstraint::arrayToObjectRecursive($validationSchema);
+        }
+
         // validate schema against whatever is defined in $validationSchema->$schema. If no
         // schema is defined, assume self::DEFAULT_SCHEMA_SPEC (currently draft-04).
         if ($this->factory->getConfig(self::CHECK_MODE_VALIDATE_SCHEMA)) {
diff --git a/src/JsonSchema/Constraints/UndefinedConstraint.php b/src/JsonSchema/Constraints/UndefinedConstraint.php
index ec43467e..a86afcac 100644
--- a/src/JsonSchema/Constraints/UndefinedConstraint.php
+++ b/src/JsonSchema/Constraints/UndefinedConstraint.php
@@ -72,8 +72,9 @@ public function validateTypes(&$value, $schema = null, JsonPointer $path, $i = n
                                                 // is not set (i.e. don't use $this->getTypeCheck() here).
             $this->checkObject(
                 $value,
-                isset($schema->properties) ? $this->factory->getSchemaStorage()->resolveRefSchema($schema->properties) : $schema,
+                $schema,
                 $path,
+                isset($schema->properties) ? $schema->properties : null,
                 isset($schema->additionalProperties) ? $schema->additionalProperties : null,
                 isset($schema->patternProperties) ? $schema->patternProperties : null,
                 $this->appliedDefaults
@@ -251,8 +252,14 @@ protected function applyDefaultValues(&$value, $schema, $path)
                 }
             }
         } elseif (isset($schema->items) && LooseTypeCheck::isArray($value)) {
+            $items = array();
+            if (LooseTypeCheck::isArray($schema->items)) {
+                $items = $schema->items;
+            } elseif (isset($schema->minItems) && count($value) < $schema->minItems) {
+                $items = array_fill(count($value), $schema->minItems - count($value), $schema->items);
+            }
             // $value is an array, and items are defined - treat as plain array
-            foreach ($schema->items as $currentItem => $itemDefinition) {
+            foreach ($items as $currentItem => $itemDefinition) {
                 if (
                     !array_key_exists($currentItem, $value)
                     && property_exists($itemDefinition, 'default')
diff --git a/src/JsonSchema/Rfc3339.php b/src/JsonSchema/Rfc3339.php
index fb2eb7d5..adca581a 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\d{2}:\d{2}:\d{2})(\.\d+)?(Z|([+-]\d{2}):?(\d{2}))$/';
+    const REGEX = '/^(\d{4}-\d{2}-\d{2}[T ]{1}\d{2}:\d{2}:\d{2})(\.\d+)?(Z|([+-]\d{2}):?(\d{2}))$/';
 
     /**
      * Try creating a DateTime instance
@@ -22,8 +22,8 @@ public static function createFromString($string)
         $dateAndTime = $matches[1];
         $microseconds = $matches[2] ?: '.000000';
         $timeZone = 'Z' !== $matches[3] ? $matches[4] . ':' . $matches[5] : '+00:00';
-
-        $dateTime = \DateTime::createFromFormat('Y-m-d\TH:i:s.uP', $dateAndTime . $microseconds . $timeZone, new \DateTimeZone('UTC'));
+        $dateFormat = strpos($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'));
 
         return $dateTime ?: null;
     }
diff --git a/src/JsonSchema/SchemaStorage.php b/src/JsonSchema/SchemaStorage.php
index 3ee081e3..9a1caeb4 100644
--- a/src/JsonSchema/SchemaStorage.php
+++ b/src/JsonSchema/SchemaStorage.php
@@ -2,6 +2,7 @@
 
 namespace JsonSchema;
 
+use JsonSchema\Constraints\BaseConstraint;
 use JsonSchema\Entity\JsonPointer;
 use JsonSchema\Exception\UnresolvableJsonPointerException;
 use JsonSchema\Iterator\ObjectIterator;
@@ -51,6 +52,23 @@ public function addSchema($id, $schema = null)
             // schemas do not have an associated URI when passed via Validator::validate().
             $schema = $this->uriRetriever->retrieve($id);
         }
+
+        // cast array schemas to object
+        if (is_array($schema)) {
+            $schema = BaseConstraint::arrayToObjectRecursive($schema);
+        }
+
+        // workaround for bug in draft-03 & draft-04 meta-schemas (id & $ref defined with incorrect format)
+        // see https://github.com/json-schema-org/JSON-Schema-Test-Suite/issues/177#issuecomment-293051367
+        if (is_object($schema) && property_exists($schema, 'id')) {
+            if ($schema->id == 'http://json-schema.org/draft-04/schema#') {
+                $schema->properties->id->format = 'uri-reference';
+            } elseif ($schema->id == 'http://json-schema.org/draft-03/schema#') {
+                $schema->properties->id->format = 'uri-reference';
+                $schema->properties->{'$ref'}->format = 'uri-reference';
+            }
+        }
+
         $objectIterator = new ObjectIterator($schema);
         foreach ($objectIterator as $toResolveSchema) {
             if (property_exists($toResolveSchema, '$ref') && is_string($toResolveSchema->{'$ref'})) {
diff --git a/src/JsonSchema/Validator.php b/src/JsonSchema/Validator.php
index 9554175f..7b6a8077 100644
--- a/src/JsonSchema/Validator.php
+++ b/src/JsonSchema/Validator.php
@@ -57,7 +57,10 @@ public function validate(&$value, $schema = null, $checkMode = null)
         $this->factory->getSchemaStorage()->addSchema(SchemaStorage::INTERNAL_PROVIDED_SCHEMA_URI, $schema);
 
         $validator = $this->factory->createInstanceFor('schema');
-        $validator->check($value, $schema);
+        $validator->check(
+            $value,
+            $this->factory->getSchemaStorage()->getSchema(SchemaStorage::INTERNAL_PROVIDED_SCHEMA_URI)
+        );
 
         $this->factory->setConfig($initialCheckMode);
 
diff --git a/tests/Constraints/DefaultPropertiesTest.php b/tests/Constraints/DefaultPropertiesTest.php
index a3b9c4e2..bcf90b2c 100644
--- a/tests/Constraints/DefaultPropertiesTest.php
+++ b/tests/Constraints/DefaultPropertiesTest.php
@@ -149,6 +149,21 @@ public function getValidTests()
                 '{"items":[{"default":null}]}',
                 '[null]'
             ),
+            array(// #21 items might be a schema (instead of an array of schema)
+                '[{}]',
+                '{"items":{"properties":{"propertyOne":{"default":"valueOne"}}}}',
+                '[{"propertyOne":"valueOne"}]'
+            ),
+            array(// #22 if items is not an array, it does not create a new item
+                '[]',
+                '{"items":{"properties":{"propertyOne":{"default":"valueOne"}}}}',
+                '[]'
+            ),
+            array(// #23 if items is a schema with a default value and minItems is present, fill the array
+                '["a"]',
+                '{"items":{"default":"b"}, "minItems": 3}',
+                '["a","b","b"]'
+            ),
         );
     }
 
diff --git a/tests/Constraints/FormatTest.php b/tests/Constraints/FormatTest.php
index ad7075d9..b035aafe 100644
--- a/tests/Constraints/FormatTest.php
+++ b/tests/Constraints/FormatTest.php
@@ -143,12 +143,12 @@ public function getValidFormats()
             array('555 320 1212', 'phone'),
 
             array('http://bluebox.org', 'uri'),
-            array('//bluebox.org', 'uri'),
-            array('/absolutePathReference/', 'uri'),
-            array('./relativePathReference/', 'uri'),
-            array('./relative:PathReference/', 'uri'),
-            array('relativePathReference/', 'uri'),
-            array('relative/Path:Reference/', 'uri'),
+            array('//bluebox.org', 'uri-reference'),
+            array('/absolutePathReference/', 'uri-reference'),
+            array('./relativePathReference/', 'uri-reference'),
+            array('./relative:PathReference/', 'uri-reference'),
+            array('relativePathReference/', 'uri-reference'),
+            array('relative/Path:Reference/', 'uri-reference'),
 
             array('info@something.edu', 'email'),
 
@@ -200,6 +200,12 @@ public function getInvalidFormats()
             array('htt:/bluebox.org', 'uri'),
             array('.relative:path/reference/', 'uri'),
             array('', 'uri'),
+            array('//bluebox.org', 'uri'),
+            array('/absolutePathReference/', 'uri'),
+            array('./relativePathReference/', 'uri'),
+            array('./relative:PathReference/', 'uri'),
+            array('relativePathReference/', 'uri'),
+            array('relative/Path:Reference/', 'uri'),
 
             array('info@somewhere', 'email'),
 
diff --git a/tests/Constraints/MinMaxPropertiesTest.php b/tests/Constraints/MinMaxPropertiesTest.php
index e4fd5a1a..2063122c 100644
--- a/tests/Constraints/MinMaxPropertiesTest.php
+++ b/tests/Constraints/MinMaxPropertiesTest.php
@@ -74,7 +74,7 @@ public function getInvalidTests()
         return array(
             array(
                 '{
-                  "value": 1
+                  "value": {}
                 }',
                 '{
                   "type": "object",
@@ -83,9 +83,27 @@ public function getInvalidTests()
                   }
                 }'
             ),
+            array(
+                '{}',
+                '{
+                  "type": "object",
+                  "properties": {
+                    "propertyOne": {
+                      "type": "string"
+                    },
+                    "propertyTwo": {
+                      "type": "string"
+                    }
+                  },
+                  "minProperties": 1
+                }'
+            ),
             array(
                 '{
-                  "value": 1
+                  "value": {
+                    "propertyOne": "valueOne",
+                    "propertyTwo": "valueTwo"
+                  }
                 }',
                 '{
                   "type": "object",
diff --git a/tests/Rfc3339Test.php b/tests/Rfc3339Test.php
index d01da520..13294d0a 100644
--- a/tests/Rfc3339Test.php
+++ b/tests/Rfc3339Test.php
@@ -35,8 +35,14 @@ public function provideValidFormats()
                 '2000-05-01T12:12:12Z',
                 \DateTime::createFromFormat('Y-m-d\TH:i:s', '2000-05-01T12:12:12', new \DateTimeZone('UTC'))
             ),
-            array('2000-05-01T12:12:12+0100', \DateTime::createFromFormat('Y-m-d\TH:i:sP', '2000-05-01T12:12:12+01:00')),
-            array('2000-05-01T12:12:12+01:00', \DateTime::createFromFormat('Y-m-d\TH:i:sP', '2000-05-01T12:12:12+01:00')),
+            array(
+                '2000-05-01T12:12:12+0100',
+                \DateTime::createFromFormat('Y-m-d\TH:i:sP', '2000-05-01T12:12:12+01:00')
+            ),
+            array(
+                '2000-05-01T12:12:12+01:00',
+                \DateTime::createFromFormat('Y-m-d\TH:i:sP', '2000-05-01T12:12:12+01:00')
+            ),
             array(
                 '2000-05-01T12:12:12.123456Z',
                 \DateTime::createFromFormat('Y-m-d\TH:i:s.u', '2000-05-01T12:12:12.123456', new \DateTimeZone('UTC'))
@@ -45,6 +51,14 @@ public function provideValidFormats()
                 '2000-05-01T12:12:12.123Z',
                 \DateTime::createFromFormat('Y-m-d\TH:i:s.u', '2000-05-01T12:12:12.123000', new \DateTimeZone('UTC'))
             ),
+            array(
+                '2000-05-01 12:12:12.123Z',
+                \DateTime::createFromFormat('Y-m-d H:i:s.u', '2000-05-01 12:12:12.123000', new \DateTimeZone('UTC'))
+            ),
+            array(
+                '2000-05-01 12:12:12.123456Z',
+                \DateTime::createFromFormat('Y-m-d H:i:s.u', '2000-05-01 12:12:12.123456', new \DateTimeZone('UTC'))
+            )
         );
     }
 
@@ -54,6 +68,8 @@ public function provideInvalidFormats()
             array('1999-1-11T00:00:00Z'),
             array('1999-01-11T00:00:00+100'),
             array('1999-01-11T00:00:00+1:00'),
+            array('1999-01-01  00:00:00Z'),
+            array('1999-1-11 00:00:00Z')
         );
     }
 }
diff --git a/tests/SchemaStorageTest.php b/tests/SchemaStorageTest.php
index 294f0f95..0e440ac8 100644
--- a/tests/SchemaStorageTest.php
+++ b/tests/SchemaStorageTest.php
@@ -289,4 +289,17 @@ public function testGetUriResolver()
         $s->addSchema('http://json-schema.org/draft-04/schema#');
         $this->assertInstanceOf('\JsonSchema\Uri\UriResolver', $s->getUriResolver());
     }
+
+    public function testMetaSchemaFixes()
+    {
+        $s = new SchemaStorage();
+        $s->addSchema('http://json-schema.org/draft-03/schema#');
+        $s->addSchema('http://json-schema.org/draft-04/schema#');
+        $draft_03 = $s->getSchema('http://json-schema.org/draft-03/schema#');
+        $draft_04 = $s->getSchema('http://json-schema.org/draft-04/schema#');
+
+        $this->assertEquals('uri-reference', $draft_03->properties->id->format);
+        $this->assertEquals('uri-reference', $draft_03->properties->{'$ref'}->format);
+        $this->assertEquals('uri-reference', $draft_04->properties->id->format);
+    }
 }