diff --git a/src/Constraint/ConstraintManager.php b/src/Constraint/ConstraintManager.php
index da2bd83..7cbd1ac 100644
--- a/src/Constraint/ConstraintManager.php
+++ b/src/Constraint/ConstraintManager.php
@@ -26,9 +26,9 @@ public function __construct($constraints = array()) {
    */
   public function getConstraints($constraint_class = NULL) {
     if ($constraint_class == NULL) {
-      return $this->constraint;
+      return $this->constraints;
     } else {
-      return $this->constraint[$constraint_class];
+      return $this->constraints[$constraint_class];
     }
   }
 
diff --git a/src/Event/EventItemizer.php b/src/Event/EventItemizer.php
index 744c0b6..ee360ba 100644
--- a/src/Event/EventItemizer.php
+++ b/src/Event/EventItemizer.php
@@ -216,7 +216,7 @@ private function createDayGranural($itemized = array()) {
 
     if ($this->event->isSameDay()) {
       if (!($this->event->getStartDate()->format('H:i') == '00:00' && $this->event->getEndDate()->format('H:i') == '23:59')) {
-        $itemized_same_day = $this->createHourlyGranular($start_date, $end_date->add(new \DateInterval('PT1M')), $interval, $start_date);
+        $itemized_same_day = $this->createHourlyGranular($start_date, $end_date->add(new \DateInterval('PT1M')), $interval);
         $itemized[EventItemizer::BAT_DAY][$sy][$sm]['d' . $sd] = -1;
         $itemized[EventItemizer::BAT_HOUR][$sy][$sm]['d' . $sd] = $itemized_same_day[EventItemizer::BAT_HOUR][$sy][$sm]['d' . $sd];
         $itemized[EventItemizer::BAT_MINUTE][$sy][$sm]['d' . $sd] = $itemized_same_day[EventItemizer::BAT_MINUTE][$sy][$sm]['d' . $sd];
@@ -225,7 +225,7 @@ private function createDayGranural($itemized = array()) {
     else {
       // Deal with the start day unless it starts on midnight precisely at which point the whole day is booked
       if (!($this->event->getStartDate()->format('H:i') == '00:00')) {
-        $itemized_start = $this->createHourlyGranular($start_date, new \DateTime($start_date->format("Y-n-j 23:59:59")), $interval, $start_date);
+        $itemized_start = $this->createHourlyGranular($start_date, new \DateTime($start_date->format("Y-n-j 23:59:59")), $interval);
         $itemized[EventItemizer::BAT_DAY][$sy][$sm]['d' . $sd] = -1;
         $itemized[EventItemizer::BAT_HOUR][$sy][$sm]['d' . $sd] = $itemized_start[EventItemizer::BAT_HOUR][$sy][$sm]['d' . $sd];
         $itemized[EventItemizer::BAT_MINUTE][$sy][$sm]['d' . $sd] = $itemized_start[EventItemizer::BAT_MINUTE][$sy][$sm]['d' . $sd];
@@ -242,7 +242,7 @@ private function createDayGranural($itemized = array()) {
         $itemized[EventItemizer::BAT_MINUTE][$ey][$em]['d' . $ed] = array();
       }
       else {
-        $itemized_end = $this->createHourlyGranular(new \DateTime($end_date->format("Y-n-j 00:00:00")), $end_date->add(new \DateInterval('PT1M')), $interval, new \DateTime($end_date->format("Y-n-j 00:00:00")));
+        $itemized_end = $this->createHourlyGranular(new \DateTime($end_date->format("Y-n-j 00:00:00")), $end_date->add(new \DateInterval('PT1M')), $interval);
         $itemized[EventItemizer::BAT_DAY][$ey][$em]['d' . $ed] = -1;
         $itemized[EventItemizer::BAT_HOUR][$ey][$em]['d' . $ed] = $itemized_end[EventItemizer::BAT_HOUR][$ey][$em]['d' . $ed];
         $itemized[EventItemizer::BAT_MINUTE][$ey][$em]['d' . $ed] = $itemized_end[EventItemizer::BAT_MINUTE][$ey][$em]['d' . $ed];
@@ -259,28 +259,31 @@ private function createDayGranural($itemized = array()) {
    * @param \DateTime $start_date
    * @param \DateTime $end_date
    * @param \DateInterval $interval
-   * @param \DateTime $period_start
    * @return array
    */
-  public function createHourlyGranular(\DateTime $start_date, \DateTime $end_date, \DateInterval $interval, \DateTime $period_start) {
+  public function createHourlyGranular(\DateTime $start_date, \DateTime $end_date, \DateInterval $interval) {
     $period = new \DatePeriod($start_date, $interval, $end_date);
 
     $itemized = array();
 
-    $start_minute = (int)$period_start->format('i');
-    $init = TRUE;
+    $start_minute = (int)$start_date->format('i');
 
     $event_value = $this->event->getValue();
 
+    $year = $start_date->format('Y');
+    $month = $start_date->format('n');
+    $day = $start_date->format('j');
+    $hour = $start_date->format('G');
+    $min = $start_date->format('i');
+
     foreach ($period as $minute) {
-      if ($init) {
+      // Re-calculate if we're at a day boundary.
+      if ($hour == 24) {
         $year = $minute->format('Y');
         $month = $minute->format('n');
         $day = $minute->format('j');
         $hour = $minute->format('G');
         $min = $minute->format('i');
-
-        $init = FALSE;
       }
 
       // Doing minutes so set the values in the minute array
@@ -304,11 +307,6 @@ public function createHourlyGranular(\DateTime $start_date, \DateTime $end_date,
         $start_minute = 0;
       }
 
-      if ($hour == 24) {
-        // Re-calculate if we're at a day boundary.
-        $init = TRUE;
-      }
-
       $min = str_pad($min, 2, 0, STR_PAD_LEFT);
     }
 
diff --git a/src/Store/DrupalDBStore.php b/src/Store/DrupalDBStore.php
index 01ea8f1..1d29116 100644
--- a/src/Store/DrupalDBStore.php
+++ b/src/Store/DrupalDBStore.php
@@ -7,6 +7,7 @@
 
 namespace Roomify\Bat\Store;
 
+use Roomify\Bat\Event\EventInterface;
 use Roomify\Bat\Event\Event;
 use Roomify\Bat\Event\EventItemizer;
 use Roomify\Bat\Store\SqlDBStore;
@@ -70,12 +71,12 @@ public function getEventData(\DateTime $start_date, \DateTime $end_date, $unit_i
   }
 
   /**
-   * @param \Roomify\Bat\Event\Event $event
+   * @param \Roomify\Bat\Event\EventInterface $event
    * @param $granularity
    *
    * @return bool
    */
-  public function storeEvent(Event $event, $granularity = Event::BAT_HOURLY) {
+  public function storeEvent(EventInterface $event, $granularity = Event::BAT_HOURLY) {
     $stored = TRUE;
     $transaction = db_transaction();
 
@@ -118,7 +119,7 @@ public function storeEvent(Event $event, $granularity = Event::BAT_HOURLY) {
           }
         }
 
-        //If we have minutes write minutes
+        // If we have minutes write minutes
         foreach ($itemized[Event::BAT_MINUTE] as $year => $months) {
           foreach ($months as $month => $days) {
             foreach ($days as $day => $hours) {
diff --git a/src/Store/SqlDBStore.php b/src/Store/SqlDBStore.php
index 1b37f3e..c788460 100644
--- a/src/Store/SqlDBStore.php
+++ b/src/Store/SqlDBStore.php
@@ -113,7 +113,7 @@ public function buildQueries(\DateTime $start_date, \DateTime $end_date, $unit_i
     $queries[Event::BAT_MINUTE] = 'SELECT * FROM ' . $this->minute_table . ' WHERE ';
 
     // Create a mock event which we will use to determine how to query the database
-    $mock_event = new Event($start_date, $end_date, new Unit(0, 0, NULL), -10);
+    $mock_event = new Event($start_date, $end_date, new Unit(0, 0, array()), -10);
     // We don't need a granular event even if we are retrieving granular data - since we don't
     // know what the event break-down is going to be we need to get the full range of data from
     // days, hours and minutes.
diff --git a/src/Store/SqlLiteDBStore.php b/src/Store/SqlLiteDBStore.php
index a9ceace..b796626 100644
--- a/src/Store/SqlLiteDBStore.php
+++ b/src/Store/SqlLiteDBStore.php
@@ -7,6 +7,7 @@
 
 namespace Roomify\Bat\Store;
 
+use Roomify\Bat\Event\EventInterface;
 use Roomify\Bat\Event\Event;
 use Roomify\Bat\Event\EventItemizer;
 use Roomify\Bat\Store\SqlDBStore;
@@ -78,12 +79,12 @@ public function getEventData(\DateTime $start_date, \DateTime $end_date, $unit_i
   }
 
   /**
-   * @param \Roomify\Bat\Event\Event $event
+   * @param \Roomify\Bat\Event\EventInterface $event
    * @param $granularity
    *
    * @return bool
    */
-  public function storeEvent(Event $event, $granularity = Event::BAT_HOURLY) {
+  public function storeEvent(EventInterface $event, $granularity = Event::BAT_HOURLY) {
     $stored = TRUE;
 
     // Get existing event data from db
diff --git a/src/Store/StoreInterface.php b/src/Store/StoreInterface.php
index 2cbc90a..3742b07 100644
--- a/src/Store/StoreInterface.php
+++ b/src/Store/StoreInterface.php
@@ -7,7 +7,7 @@
 
 namespace Roomify\Bat\Store;
 
-use Roomify\Bat\Event\Event;
+use Roomify\Bat\Event\EventInterface;
 
 /**
  * A store is a place where event data is held. The purpose of separating these
@@ -35,5 +35,6 @@ public function getEventData(\DateTime $start_date, \DateTime $end_date, $unit_i
    *
    * @return boolean
    */
-  public function storeEvent(Event $event, $granularity);
+  public function storeEvent(EventInterface $event, $granularity);
+
 }
diff --git a/src/Valuator/AbstractValuator.php b/src/Valuator/AbstractValuator.php
index 92c5ba5..91461be 100644
--- a/src/Valuator/AbstractValuator.php
+++ b/src/Valuator/AbstractValuator.php
@@ -76,10 +76,9 @@ public function setEndDate(\DateTime $end_date) {
   }
 
   /**
-   * @param \DateTime $end_date
    * @return \DateTime
    */
-  public function getEndDate(\DateTime $end_date) {
+  public function getEndDate() {
     return $this->end_date;
   }
 
diff --git a/tests/EventTest.php b/tests/EventTest.php
index ef39cad..000326a 100644
--- a/tests/EventTest.php
+++ b/tests/EventTest.php
@@ -554,4 +554,24 @@ public function testEventItemizeEventOneDay() {
     $this->assertEquals($itemized[Event::BAT_DAY]['2016']['3']['d1'], '5');
   }
 
+  public function testCreateHourlyGranular() {
+    $event_state = 5;
+    $start_date = new \DateTime('2016-01-30 12:12');
+    $end_date = new \DateTime('2016-02-02 12:12');
+    $unit = new Unit(1, 2, array());
+
+    $event = new Event($start_date, $end_date, $unit, $event_state);
+
+    $itemizer = new EventItemizer($event);
+    $itemized = $itemizer->createHourlyGranular($start_date, $end_date, new \DateInterval('PT1M'));
+
+    $this->assertEquals($itemized[Event::BAT_HOUR]['2016']['1']['d30']['h12'], '-1');
+
+    $this->assertEquals($itemized[Event::BAT_MINUTE]['2016']['1']['d30']['h12']['m12'], '5');
+
+    $this->assertEquals($itemized[Event::BAT_HOUR]['2016']['2']['d2']['h12'], '-1');
+
+    $this->assertEquals($itemized[Event::BAT_MINUTE]['2016']['2']['d2']['h12']['m11'], '5');
+  }
+
 }