diff --git a/src/Faker/Generator.php b/src/Faker/Generator.php
index 0115870438..0a4e050294 100644
--- a/src/Faker/Generator.php
+++ b/src/Faker/Generator.php
@@ -94,12 +94,12 @@
  * @property \DateTime $dateTimeThisYear
  * @property \DateTime $dateTimeThisMonth
  * @property string    $amPm
- * @property int       $dayOfMonth
- * @property int       $dayOfWeek
- * @property int       $month
+ * @property string    $dayOfMonth
+ * @property string    $dayOfWeek
+ * @property string    $month
  * @property string    $monthName
- * @property int       $year
- * @property int       $century
+ * @property string    $year
+ * @property string    $century
  * @property string    $timezone
  * @method string amPm($max = 'now')
  * @method string date($format = 'Y-m-d', $max = 'now')
@@ -109,7 +109,7 @@
  * @method string month($max = 'now')
  * @method string monthName($max = 'now')
  * @method string time($format = 'H:i:s', $max = 'now')
- * @method string unixTime($max = 'now')
+ * @method int unixTime($max = 'now')
  * @method string year($max = 'now')
  * @method \DateTime dateTime($max = 'now', $timezone = null)
  * @method \DateTime dateTimeAd($max = 'now', $timezone = null)
diff --git a/src/Faker/Provider/DateTime.php b/src/Faker/Provider/DateTime.php
index 6fd50b1cc7..fb0f474b2a 100644
--- a/src/Faker/Provider/DateTime.php
+++ b/src/Faker/Provider/DateTime.php
@@ -8,6 +8,10 @@ class DateTime extends Base
 
     protected static $defaultTimezone = null;
 
+    /**
+     * @param string|float|int $max
+     * @return int|false
+     */
     protected static function getMaxTimestamp($max = 'now')
     {
         if (is_numeric($max)) {
@@ -56,7 +60,7 @@ public static function dateTime($max = 'now', $timezone = null)
      * Get a datetime object for a date between January 1, 001 and now
      *
      * @param \DateTime|int|string $max maximum timestamp used as random end limit, default to "now"
-     * @param string $timezone time zone in which the date time should be set, default to DateTime::$defaultTimezone, if set, otherwise the result of `date_default_timezone_get`
+     * @param string|null $timezone time zone in which the date time should be set, default to DateTime::$defaultTimezone, if set, otherwise the result of `date_default_timezone_get`
      * @example DateTime('1265-03-22 21:15:52')
      * @return \DateTime
      * @see http://php.net/manual/en/timezones.php
@@ -115,7 +119,7 @@ public static function time($format = 'H:i:s', $max = 'now')
      *
      * @param \DateTime|string $startDate Defaults to 30 years ago
      * @param \DateTime|string $endDate   Defaults to "now"
-     * @param string $timezone time zone in which the date time should be set, default to DateTime::$defaultTimezone, if set, otherwise the result of `date_default_timezone_get`
+     * @param string|null $timezone time zone in which the date time should be set, default to DateTime::$defaultTimezone, if set, otherwise the result of `date_default_timezone_get`
      * @example DateTime('1999-02-02 11:42:52')
      * @return \DateTime
      * @see http://php.net/manual/en/timezones.php
@@ -145,7 +149,7 @@ public static function dateTimeBetween($startDate = '-30 years', $endDate = 'now
      *
      * @param string $date      Defaults to 30 years ago
      * @param string $interval  Defaults to 5 days after
-     * @param string $timezone time zone in which the date time should be set, default to DateTime::$defaultTimezone, if set, otherwise the result of `date_default_timezone_get`
+     * @param string|null $timezone time zone in which the date time should be set, default to DateTime::$defaultTimezone, if set, otherwise the result of `date_default_timezone_get`
      * @example dateTimeInInterval('1999-02-02 11:42:52', '+ 5 days')
      * @return \DateTime
      * @see http://php.net/manual/en/timezones.php
@@ -170,7 +174,7 @@ public static function dateTimeInInterval($date = '-30 years', $interval = '+5 d
 
     /**
      * @param \DateTime|int|string $max maximum timestamp used as random end limit, default to "now"
-     * @param string $timezone time zone in which the date time should be set, default to DateTime::$defaultTimezone, if set, otherwise the result of `date_default_timezone_get`
+     * @param string|null $timezone time zone in which the date time should be set, default to DateTime::$defaultTimezone, if set, otherwise the result of `date_default_timezone_get`
      * @example DateTime('1964-04-04 11:02:02')
      * @return \DateTime
      */
@@ -181,7 +185,7 @@ public static function dateTimeThisCentury($max = 'now', $timezone = null)
 
     /**
      * @param \DateTime|int|string $max maximum timestamp used as random end limit, default to "now"
-     * @param string $timezone time zone in which the date time should be set, default to DateTime::$defaultTimezone, if set, otherwise the result of `date_default_timezone_get`
+     * @param string|null $timezone time zone in which the date time should be set, default to DateTime::$defaultTimezone, if set, otherwise the result of `date_default_timezone_get`
      * @example DateTime('2010-03-10 05:18:58')
      * @return \DateTime
      */
@@ -192,7 +196,7 @@ public static function dateTimeThisDecade($max = 'now', $timezone = null)
 
     /**
      * @param \DateTime|int|string $max maximum timestamp used as random end limit, default to "now"
-     * @param string $timezone time zone in which the date time should be set, default to DateTime::$defaultTimezone, if set, otherwise the result of `date_default_timezone_get`
+     * @param string|null $timezone time zone in which the date time should be set, default to DateTime::$defaultTimezone, if set, otherwise the result of `date_default_timezone_get`
      * @example DateTime('2011-09-19 09:24:37')
      * @return \DateTime
      */
@@ -203,7 +207,7 @@ public static function dateTimeThisYear($max = 'now', $timezone = null)
 
     /**
      * @param \DateTime|int|string $max maximum timestamp used as random end limit, default to "now"
-     * @param string $timezone time zone in which the date time should be set, default to DateTime::$defaultTimezone, if set, otherwise the result of `date_default_timezone_get`
+     * @param string|null $timezone time zone in which the date time should be set, default to DateTime::$defaultTimezone, if set, otherwise the result of `date_default_timezone_get`
      * @example DateTime('2011-10-05 12:51:46')
      * @return \DateTime
      */
@@ -264,8 +268,8 @@ public static function monthName($max = 'now')
 
     /**
      * @param \DateTime|int|string $max maximum timestamp used as random end limit, default to "now"
-     * @return int
-     * @example 1673
+     * @return string
+     * @example '1673'
      */
     public static function year($max = 'now')
     {
@@ -294,9 +298,9 @@ public static function timezone()
      * Internal method to set the time zone on a DateTime.
      *
      * @param \DateTime $dt
-     * @param string $timezone
+     * @param string|null $timezone
      *
-     * @return $this
+     * @return \DateTime
      */
     private static function setTimezone(\DateTime $dt, $timezone)
     {
@@ -318,13 +322,17 @@ public static function setDefaultTimezone($timezone = null)
     /**
      * Gets default time zone.
      *
-     * @return string
+     * @return string|null
      */
     public static function getDefaultTimezone()
     {
         return static::$defaultTimezone;
     }
 
+    /**
+     * @param string|null $timezone
+     * @return null|string
+     */
     private static function resolveTimezone($timezone)
     {
         return ((null === $timezone) ? ((null === static::$defaultTimezone) ? date_default_timezone_get() : static::$defaultTimezone) : $timezone);