diff --git a/publication_date.api.php b/publication_date.api.php
index a85c62b..27c8757 100644
--- a/publication_date.api.php
+++ b/publication_date.api.php
@@ -10,7 +10,9 @@
  * database on node update/insert.
  *
  * @param integer $published_at
- *   A Unix timestamp representing the publication date to be altered.
+ *   A Unix timestamp representing the publication date to be altered. If no
+ *   publication date has been set then $published_at should equal the defined
+ *   constant PUBLICATION_DATE_DEFAULT.
  * @param object $node
  *   The node object.
  * @param string $op
@@ -24,11 +26,6 @@ function hook_publication_date_alter(&$published_at, $node, $op) {
   // Check if the node is being published.
   if ($node->status == 1) {
     // If a future publication date was set, change it to the curret time.
-    $now = REQUEST_TIME;
-    $published_at = ($published_at > $now) ? $now : $published_at;
-  }
-  else {
-    // If the node isn't published then reset the published date to zero.
-    $published_at = 0;
+    $published_at = ($published_at > REQUEST_TIME) ? REQUEST_TIME : $published_at;
   }
 }
diff --git a/publication_date.install b/publication_date.install
index ef67aae..d9b6816 100755
--- a/publication_date.install
+++ b/publication_date.install
@@ -74,3 +74,13 @@ function publication_date_uninstall() {
   variable_del('publication_date_popup_year_start');
   variable_del('publication_date_popup_year_end');
 }
+
+/**
+* Change default published_at value from 0 to 2147483647.
+*/
+function publication_date_update_7001() {
+  db_update('publication_date')
+    ->fields(array('published_at' => 2147483647))
+    ->condition('published_at', 0)
+    ->execute();
+}
diff --git a/publication_date.module b/publication_date.module
index 5289b2c..a3dab49 100755
--- a/publication_date.module
+++ b/publication_date.module
@@ -6,11 +6,38 @@
  */
 
 /**
+ * Define the value stored in the database when a node is unpublished and no
+ * publication date has been set. We use the largest number that the database
+ * field can hold so unpublished nodes will appear newer than published nodes
+ * when sorted by publication date.
+ */
+define('PUBLICATION_DATE_DEFAULT', 2147483647);
+
+/**
  * Implements hook_node_load().
+ *
+ * For each node we set two properties...
+ *   - published_at: Equals the publication date in Epoc time, if one has been
+ *     set, or NULL otherwise.
+ *   - published_at_or_now: Equals published_at if a publication date has been
+ *     set, or the current REQUEST_TIME if it hasn't.
  */
 function publication_date_node_load($nodes, $types) {
   foreach ($nodes as $node) {
-    $node->published_at = _publication_date_get_date($node->nid);
+    // Get the publication date from the database.
+    $published_at = _publication_date_get_date($node->nid);
+    // If a publication date has been set, we add it to the node object in both
+    // the published_at and published_at_or_now properties.
+    if ($published_at) {
+      $node->published_at = $published_at;
+      $node->published_at_or_now = $published_at;
+    }
+    // If a publication date has not yet been set, we set published_at to NULL
+    // and published_at_or_now to REQUEST_TIME.
+    else {
+      $node->published_at = NULL;
+      $node->published_at_or_now = REQUEST_TIME;
+    }
   }
 }
 
@@ -54,12 +81,20 @@ function publication_date_node_delete($node) {
  * @see hook_node_update()
  */
 function _publication_date_set_date($node, $op = '') {
-  // Set a default publication date value.
-  $published_at = empty($node->published_at) ? 0 : $node->published_at;
-
-  // If no publication date has been set and the node is published then use
-  // REQUEST_TIME. Otherwise, use the default publication date.
-  $published_at = ($published_at == 0 && $node->status == 1) ? REQUEST_TIME : $published_at;
+  // If a publication date has already been set then retain it.
+  if (!empty($node->published_at)) {
+    $published_at = $node->published_at;
+  }
+  // Otherwise, if no publication date has been set and the node is published
+  // then set the publication date to REQUEST_TIME.
+  elseif ($node->status == 1) {
+    $published_at = REQUEST_TIME;
+  }
+  // Otherwise, if no publication date has been set and the node is unpublished
+  // then store the default publication date.
+  else {
+    $published_at = PUBLICATION_DATE_DEFAULT;
+  }
 
   // Allow other modules to alter the publication date before it is saved.
   drupal_alter('publication_date', $published_at, $node, $op);
@@ -85,7 +120,8 @@ function _publication_date_set_date($node, $op = '') {
  * @see hook_node_load()
  */
 function _publication_date_get_date($nid) {
-  $date = db_query("SELECT published_at FROM {publication_date} WHERE nid = :nid", array(':nid' => $nid))->fetchField();
+  $published_at = db_query("SELECT published_at FROM {publication_date} WHERE nid = :nid", array(':nid' => $nid))->fetchField();
+  $date = (empty($published_at) || $published_at == PUBLICATION_DATE_DEFAULT) ? FALSE : $published_at;
   return $date;
 }
 
@@ -109,7 +145,7 @@ function publication_date_form_node_form_alter(&$form, &$form_state, $form_id) {
   $node = $form["#node"];
 
   // If this is an existing node then get the currently set publication date.
-  $published_at = ($form['nid'] !== NULL && isset($node->published_at) && $node->published_at) ? $node->published_at : 0;
+  $published_at = ($form['nid'] == NULL || empty($node->published_at)) ? NULL : $node->published_at;
 
   // Check if the user has permission to edit the publication date.
   $pubdate_access = user_access('set any published on date') || user_access('set ' . $node->type . ' published on date');
@@ -191,9 +227,9 @@ function publication_date_pubdate_validate($form, &$form_state) {
  * deal with.
  */
 function publication_date_pubdate_submit($form, &$form_state) {
-  // Set $node->published_at to the publication date field value, if it was set,
-  // or zero if it was not.
-  $form_state['node']->published_at = empty($form_state['values']['pubdate']) ? 0 : strtotime(($form_state['values']['pubdate']));
+  // Set $node->published_at to the publication date field value if it was set,
+  // or NULL if it was not.
+  $form_state['node']->published_at = empty($form_state['values']['pubdate']) ? NULL : strtotime(($form_state['values']['pubdate']));
 }
 
 /**
@@ -251,7 +287,13 @@ function publication_date_entity_property_info_alter(&$info) {
     'label' => t('Published at'),
     'description' => t('The publication date of the node.'),
     'type' => 'date',
-    'getter callback' => '_publication_date_entity_property_getter',
+    'getter callback' => '_publication_date_published_at_getter',
+  );
+  $properties['published_at_or_now'] = array(
+    'label' => t('Published at or now'),
+    'description' => t('The publication date of the node, or the current time if no date has been set.'),
+    'type' => 'date',
+    'getter callback' => '_publication_date_published_at_or_now_getter',
   );
 }
 
@@ -264,11 +306,24 @@ function publication_date_entity_property_info_alter(&$info) {
  * @return integer
  *   The publication date as a timestamp get from the entity.
  */
-function _publication_date_entity_property_getter($entity) {
+function _publication_date_published_at_getter($entity) {
   return $entity->published_at;
 }
 
 /**
+ * Publication date or now getter for hook_entity_property_info_alter()
+ *
+ * @param $entity
+ *   The entity object.
+ *
+ * @return integer
+ *   The publication date (or REQUEST_TIME) as a timestamp get from the entity.
+ */
+function _publication_date_published_at_or_now_getter($entity) {
+  return $entity->published_at_or_now;
+}
+
+/**
  * Implements hook_clone_node_alter().
  *
  * Reset the publication date when a node is cloned using the Node Clone module.
@@ -277,6 +332,7 @@ function _publication_date_entity_property_getter($entity) {
  */
 function publication_date_clone_node_alter(&$node, $context) {
   $node->published_at = NULL;
+  $node->published_at_or_now = REQUEST_TIME;
 }
 
 /**
diff --git a/tests/publication_date.test b/tests/publication_date.test
index e7e4309..39d97af 100644
--- a/tests/publication_date.test
+++ b/tests/publication_date.test
@@ -35,6 +35,7 @@ class PublicationDateTestCase extends DrupalWebTestCase {
     $node = $this->drupalCreateNode(array('status' => 0));
     $unpublished_node = node_load($node->nid);
     $this->assertTrue(empty($unpublished_node->published_at), 'Published date is initially empty');
+    $this->assertTrue($unpublished_node->published_at_or_now == REQUEST_TIME, 'Published at or now date is REQUEST_TIME');
 
     // Publish the node.
     $unpublished_node->status =1;
@@ -42,6 +43,7 @@ class PublicationDateTestCase extends DrupalWebTestCase {
     $published_node = node_load($node->nid);
     $this->assertTrue(is_numeric($published_node->published_at), 'Published date is integer/numberic once published');
     $this->assertTrue($published_node->published_at == REQUEST_TIME, 'Published date is REQUEST_TIME');
+    $this->assertTrue($unpublished_node->published_at_or_now == $published_node->published_at, 'Published at or now date equals published date');
 
     // Remember time.
     $time = $published_node->published_at;
@@ -63,6 +65,7 @@ class PublicationDateTestCase extends DrupalWebTestCase {
     node_save($unpublished_node);
     $unpublished_node = node_load($node->nid);
     $this->assertTrue($unpublished_node->published_at == $time, 'Custom published date is saved');
+    $this->assertTrue($unpublished_node->published_at_or_now == $time, 'Published at or now date equals published date');
 
     // Republish the node and check that the field value is maintained.
     $unpublished_node->status = 1;