diff --git a/.gitignore b/.gitignore
index 629d61a2..f7076ff9 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,4 +1,3 @@
-/composer.lock
 /vendor
 /bin
 !/bin/validate-json
diff --git a/.scrutinizer.yml b/.scrutinizer.yml
new file mode 100644
index 00000000..730b1fd4
--- /dev/null
+++ b/.scrutinizer.yml
@@ -0,0 +1,5 @@
+before_commands:
+  - composer install --dev
+
+tools:
+  php_analyzer: true
diff --git a/.travis.yml b/.travis.yml
index 5f04debf..b4d33f77 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -5,6 +5,6 @@ php:
   - 5.4
 
 before_script:
-  - composer install
+  - composer install --dev
 
 script: phpunit --coverage-text
diff --git a/composer.json b/composer.json
index 5505c225..72973b60 100644
--- a/composer.json
+++ b/composer.json
@@ -36,10 +36,10 @@
         }
     }],
     "require": {
-        "php": ">=5.3.0",
-        "json-schema/JSON-Schema-Test-Suite": "1.1.0"
+        "php": ">=5.3.0"
     },
     "require-dev": {
+        "json-schema/JSON-Schema-Test-Suite": "1.1.0",
         "phpunit/phpunit": "~3.7.0"
     },
     "autoload": {
diff --git a/composer.lock b/composer.lock
new file mode 100644
index 00000000..f6dbc20d
--- /dev/null
+++ b/composer.lock
@@ -0,0 +1,439 @@
+{
+    "_readme": [
+        "This file locks the dependencies of your project to a known state",
+        "Read more about it at http://getcomposer.org/doc/01-basic-usage.md#composer-lock-the-lock-file"
+    ],
+    "hash": "1fe912d713c53eb855101dd82843cecf",
+    "packages": [
+
+    ],
+    "packages-dev": [
+        {
+            "name": "json-schema/JSON-Schema-Test-Suite",
+            "version": "1.1.0",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/json-schema/JSON-Schema-Test-Suite",
+                "reference": "1.1.0"
+            },
+            "type": "library"
+        },
+        {
+            "name": "phpunit/php-code-coverage",
+            "version": "1.2.11",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/sebastianbergmann/php-code-coverage.git",
+                "reference": "1.2.11"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/sebastianbergmann/php-code-coverage/zipball/1.2.11",
+                "reference": "1.2.11",
+                "shasum": ""
+            },
+            "require": {
+                "php": ">=5.3.3",
+                "phpunit/php-file-iterator": ">=1.3.0@stable",
+                "phpunit/php-text-template": ">=1.1.1@stable",
+                "phpunit/php-token-stream": ">=1.1.3@stable"
+            },
+            "require-dev": {
+                "phpunit/phpunit": "3.7.*"
+            },
+            "suggest": {
+                "ext-dom": "*",
+                "ext-xdebug": ">=2.0.5"
+            },
+            "type": "library",
+            "autoload": {
+                "classmap": [
+                    "PHP/"
+                ]
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "include-path": [
+                ""
+            ],
+            "license": [
+                "BSD-3-Clause"
+            ],
+            "authors": [
+                {
+                    "name": "Sebastian Bergmann",
+                    "email": "sb@sebastian-bergmann.de",
+                    "role": "lead"
+                }
+            ],
+            "description": "Library that provides collection, processing, and rendering functionality for PHP code coverage information.",
+            "homepage": "https://github.com/sebastianbergmann/php-code-coverage",
+            "keywords": [
+                "coverage",
+                "testing",
+                "xunit"
+            ],
+            "time": "2013-05-23 18:23:24"
+        },
+        {
+            "name": "phpunit/php-file-iterator",
+            "version": "1.3.3",
+            "source": {
+                "type": "git",
+                "url": "git://github.com/sebastianbergmann/php-file-iterator.git",
+                "reference": "1.3.3"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://github.com/sebastianbergmann/php-file-iterator/zipball/1.3.3",
+                "reference": "1.3.3",
+                "shasum": ""
+            },
+            "require": {
+                "php": ">=5.3.3"
+            },
+            "type": "library",
+            "autoload": {
+                "classmap": [
+                    "File/"
+                ]
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "include-path": [
+                ""
+            ],
+            "license": [
+                "BSD-3-Clause"
+            ],
+            "authors": [
+                {
+                    "name": "Sebastian Bergmann",
+                    "email": "sb@sebastian-bergmann.de",
+                    "role": "lead"
+                }
+            ],
+            "description": "FilterIterator implementation that filters files based on a list of suffixes.",
+            "homepage": "http://www.phpunit.de/",
+            "keywords": [
+                "filesystem",
+                "iterator"
+            ],
+            "time": "2012-10-11 04:44:38"
+        },
+        {
+            "name": "phpunit/php-text-template",
+            "version": "1.1.4",
+            "source": {
+                "type": "git",
+                "url": "git://github.com/sebastianbergmann/php-text-template.git",
+                "reference": "1.1.4"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://github.com/sebastianbergmann/php-text-template/zipball/1.1.4",
+                "reference": "1.1.4",
+                "shasum": ""
+            },
+            "require": {
+                "php": ">=5.3.3"
+            },
+            "type": "library",
+            "autoload": {
+                "classmap": [
+                    "Text/"
+                ]
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "include-path": [
+                ""
+            ],
+            "license": [
+                "BSD-3-Clause"
+            ],
+            "authors": [
+                {
+                    "name": "Sebastian Bergmann",
+                    "email": "sb@sebastian-bergmann.de",
+                    "role": "lead"
+                }
+            ],
+            "description": "Simple template engine.",
+            "homepage": "https://github.com/sebastianbergmann/php-text-template/",
+            "keywords": [
+                "template"
+            ],
+            "time": "2012-10-31 11:15:28"
+        },
+        {
+            "name": "phpunit/php-timer",
+            "version": "1.0.4",
+            "source": {
+                "type": "git",
+                "url": "git://github.com/sebastianbergmann/php-timer.git",
+                "reference": "1.0.4"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://github.com/sebastianbergmann/php-timer/zipball/1.0.4",
+                "reference": "1.0.4",
+                "shasum": ""
+            },
+            "require": {
+                "php": ">=5.3.3"
+            },
+            "type": "library",
+            "autoload": {
+                "classmap": [
+                    "PHP/"
+                ]
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "include-path": [
+                ""
+            ],
+            "license": [
+                "BSD-3-Clause"
+            ],
+            "authors": [
+                {
+                    "name": "Sebastian Bergmann",
+                    "email": "sb@sebastian-bergmann.de",
+                    "role": "lead"
+                }
+            ],
+            "description": "Utility class for timing",
+            "homepage": "http://www.phpunit.de/",
+            "keywords": [
+                "timer"
+            ],
+            "time": "2012-10-11 04:45:58"
+        },
+        {
+            "name": "phpunit/php-token-stream",
+            "version": "1.1.5",
+            "source": {
+                "type": "git",
+                "url": "git://github.com/sebastianbergmann/php-token-stream.git",
+                "reference": "1.1.5"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://github.com/sebastianbergmann/php-token-stream/zipball/1.1.5",
+                "reference": "1.1.5",
+                "shasum": ""
+            },
+            "require": {
+                "ext-tokenizer": "*",
+                "php": ">=5.3.3"
+            },
+            "type": "library",
+            "autoload": {
+                "classmap": [
+                    "PHP/"
+                ]
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "include-path": [
+                ""
+            ],
+            "license": [
+                "BSD-3-Clause"
+            ],
+            "authors": [
+                {
+                    "name": "Sebastian Bergmann",
+                    "email": "sb@sebastian-bergmann.de",
+                    "role": "lead"
+                }
+            ],
+            "description": "Wrapper around PHP's tokenizer extension.",
+            "homepage": "http://www.phpunit.de/",
+            "keywords": [
+                "tokenizer"
+            ],
+            "time": "2012-10-11 04:47:14"
+        },
+        {
+            "name": "phpunit/phpunit",
+            "version": "3.7.21",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/sebastianbergmann/phpunit.git",
+                "reference": "3.7.21"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/sebastianbergmann/phpunit/zipball/3.7.21",
+                "reference": "3.7.21",
+                "shasum": ""
+            },
+            "require": {
+                "ext-dom": "*",
+                "ext-pcre": "*",
+                "ext-reflection": "*",
+                "ext-spl": "*",
+                "php": ">=5.3.3",
+                "phpunit/php-code-coverage": ">=1.2.1,<1.3.0",
+                "phpunit/php-file-iterator": ">=1.3.1",
+                "phpunit/php-text-template": ">=1.1.1",
+                "phpunit/php-timer": ">=1.0.2,<1.1.0",
+                "phpunit/phpunit-mock-objects": ">=1.2.0,<1.3.0",
+                "symfony/yaml": ">=2.0,<3.0"
+            },
+            "require-dev": {
+                "pear-pear/pear": "1.9.4"
+            },
+            "suggest": {
+                "ext-json": "*",
+                "ext-simplexml": "*",
+                "ext-tokenizer": "*",
+                "phpunit/php-invoker": ">=1.1.0,<1.2.0"
+            },
+            "bin": [
+                "composer/bin/phpunit"
+            ],
+            "type": "library",
+            "extra": {
+                "branch-alias": {
+                    "dev-master": "3.7.x-dev"
+                }
+            },
+            "autoload": {
+                "classmap": [
+                    "PHPUnit/"
+                ]
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "include-path": [
+                "",
+                "../../symfony/yaml/"
+            ],
+            "license": [
+                "BSD-3-Clause"
+            ],
+            "authors": [
+                {
+                    "name": "Sebastian Bergmann",
+                    "email": "sebastian@phpunit.de",
+                    "role": "lead"
+                }
+            ],
+            "description": "The PHP Unit Testing framework.",
+            "homepage": "http://www.phpunit.de/",
+            "keywords": [
+                "phpunit",
+                "testing",
+                "xunit"
+            ],
+            "time": "2013-05-23 18:54:29"
+        },
+        {
+            "name": "phpunit/phpunit-mock-objects",
+            "version": "1.2.3",
+            "source": {
+                "type": "git",
+                "url": "git://github.com/sebastianbergmann/phpunit-mock-objects.git",
+                "reference": "1.2.3"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://github.com/sebastianbergmann/phpunit-mock-objects/archive/1.2.3.zip",
+                "reference": "1.2.3",
+                "shasum": ""
+            },
+            "require": {
+                "php": ">=5.3.3",
+                "phpunit/php-text-template": ">=1.1.1@stable"
+            },
+            "suggest": {
+                "ext-soap": "*"
+            },
+            "type": "library",
+            "autoload": {
+                "classmap": [
+                    "PHPUnit/"
+                ]
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "include-path": [
+                ""
+            ],
+            "license": [
+                "BSD-3-Clause"
+            ],
+            "authors": [
+                {
+                    "name": "Sebastian Bergmann",
+                    "email": "sb@sebastian-bergmann.de",
+                    "role": "lead"
+                }
+            ],
+            "description": "Mock Object library for PHPUnit",
+            "homepage": "https://github.com/sebastianbergmann/phpunit-mock-objects/",
+            "keywords": [
+                "mock",
+                "xunit"
+            ],
+            "time": "2013-01-13 10:24:48"
+        },
+        {
+            "name": "symfony/yaml",
+            "version": "v2.2.1",
+            "target-dir": "Symfony/Component/Yaml",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/symfony/Yaml.git",
+                "reference": "v2.2.1"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/symfony/Yaml/zipball/v2.2.1",
+                "reference": "v2.2.1",
+                "shasum": ""
+            },
+            "require": {
+                "php": ">=5.3.3"
+            },
+            "type": "library",
+            "extra": {
+                "branch-alias": {
+                    "dev-master": "2.2-dev"
+                }
+            },
+            "autoload": {
+                "psr-0": {
+                    "Symfony\\Component\\Yaml\\": ""
+                }
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "MIT"
+            ],
+            "authors": [
+                {
+                    "name": "Fabien Potencier",
+                    "email": "fabien@symfony.com"
+                },
+                {
+                    "name": "Symfony Community",
+                    "homepage": "http://symfony.com/contributors"
+                }
+            ],
+            "description": "Symfony Yaml Component",
+            "homepage": "http://symfony.com",
+            "time": "2013-03-23 07:49:54"
+        }
+    ],
+    "aliases": [
+
+    ],
+    "minimum-stability": "stable",
+    "stability-flags": [
+
+    ],
+    "platform": {
+        "php": ">=5.3.0"
+    },
+    "platform-dev": [
+
+    ]
+}
diff --git a/src/JsonSchema/Constraints/Undefined.php b/src/JsonSchema/Constraints/Undefined.php
index 5316000d..5e8a8401 100644
--- a/src/JsonSchema/Constraints/Undefined.php
+++ b/src/JsonSchema/Constraints/Undefined.php
@@ -139,6 +139,20 @@ protected function validateCommonProperties($value, $schema = null, $path = null
             }
         }
 
+        // Verify minimum and maximum number of properties
+        if (is_object($value)) {
+            if (isset($schema->minProperties)) {
+                if (count(get_object_vars($value)) < $schema->minProperties) {
+                    $this->addError($path, "must contain a minimum of " + $schema->minProperties + " properties");
+                }
+            }
+            if (isset($schema->maxProperties)) {
+                if (count(get_object_vars($value)) > $schema->maxProperties) {
+                    $this->addError($path, "must contain no more than " + $schema->maxProperties + " properties");
+                }
+            }
+        }
+
         // Verify that dependencies are met
         if (is_object($value) && isset($schema->dependencies)) {
             $this->validateDependencies($value, $schema->dependencies, $path);
diff --git a/tests/JsonSchema/Tests/Drafts/Draft4Test.php b/tests/JsonSchema/Tests/Drafts/Draft4Test.php
index e51e06a5..af90fe47 100644
--- a/tests/JsonSchema/Tests/Drafts/Draft4Test.php
+++ b/tests/JsonSchema/Tests/Drafts/Draft4Test.php
@@ -19,8 +19,6 @@ protected function getSkippedTests()
             'allOf.json',
             'anyOf.json',
             'definitions.json',
-            'maxProperties.json',
-            'minProperties.json',
             'multipleOf.json',
             'not.json',
             'oneOf.json',