diff --git a/feeds.module b/feeds.module
index cac8fc4..a38643a 100644
--- a/feeds.module
+++ b/feeds.module
@@ -407,9 +407,9 @@ function feeds_admin_paths() {
  * Menu loader callback.
  */
 function feeds_importer_load($id) {
-  $feed = feeds_importer($id);
-  if ($feed->doesExist()) {
-    return $feed;
+  $importer = feeds_importer($id);
+  if ($importer->doesExist()) {
+    return $importer;
   }
   return FALSE;
 }
diff --git a/feeds_ui/feeds_ui.test b/feeds_ui/feeds_ui.test
index e0a56bd..2f79714 100644
--- a/feeds_ui/feeds_ui.test
+++ b/feeds_ui/feeds_ui.test
@@ -162,11 +162,11 @@ class FeedsUIUserInterfaceTestCase extends FeedsWebTestCase {
   }
 
   /**
-   *  Edit an importer configuration
+   * Edits an importer configuration.
    *
-   * @param $name
+   * @param string $name
    *   The natural name of the feed.
-   * @param $id
+   * @param string $id
    *   The persistent id of the feed.
    */
   protected function doEditFeedsConfiguration($name = 'Syndication', $id = 'syndication') {
diff --git a/includes/FeedsConfigurable.inc b/includes/FeedsConfigurable.inc
index 48e2494..c305f6a 100644
--- a/includes/FeedsConfigurable.inc
+++ b/includes/FeedsConfigurable.inc
@@ -91,6 +91,10 @@ abstract class FeedsConfigurable {
 
   /**
    * Determine whether this object is persistent.
+   *
+   * @return bool
+   *   True if the object is persistent.
+   *   False otherwise.
    */
   public function doesExist() {
     return ($this->export_type == FEEDS_EXPORT_NONE) ? FALSE : TRUE;
@@ -98,6 +102,10 @@ abstract class FeedsConfigurable {
 
   /**
    * Determine whether this object is enabled.
+   *
+   * @return bool
+   *   True if the object is enabled.
+   *   False otherwise.
    */
   public function isEnabled() {
     return $this->disabled ? FALSE : TRUE;
diff --git a/includes/FeedsSource.inc b/includes/FeedsSource.inc
index 64a0be1..6305188 100644
--- a/includes/FeedsSource.inc
+++ b/includes/FeedsSource.inc
@@ -707,21 +707,52 @@ class FeedsSource extends FeedsConfigurable {
   }
 
   /**
+   * Checks whether or not the source configuration is valid.
+   *
+   * @return bool
+   *   True if it is valid.
+   *   False otherwise.
+   */
+  public function hasValidConfiguration() {
+    // If there is no feed nid given, there must be no content type specified.
+    $standalone = empty($this->feed_nid) && empty($this->importer->config['content_type']);
+
+    // If there is a feed nid given, there must be a content type specified.
+    $attached = !empty($this->feed_nid) && !empty($this->importer->config['content_type']);
+
+    if ($standalone || $attached) {
+      return TRUE;
+    }
+    return FALSE;
+  }
+
+  /**
+   * Overrides FeedsConfigurable::doesExist().
+   *
+   * Checks the following:
+   * - If the importer is persistent (= defined in code or DB).
+   * - If the source is persistent (= defined in DB).
+   */
+  public function doesExist() {
+    return $this->importer->doesExist() && parent::doesExist();
+  }
+
+  /**
    * Only return source if configuration is persistent and valid.
    *
    * @see FeedsConfigurable::existing().
    */
   public function existing() {
-    // If there is no feed nid given, there must be no content type specified.
-    // If there is a feed nid given, there must be a content type specified.
-    // Ensure that importer is persistent (= defined in code or DB).
-    // Ensure that source is persistent (= defined in DB).
-    if ((empty($this->feed_nid) && empty($this->importer->config['content_type'])) ||
-        (!empty($this->feed_nid) && !empty($this->importer->config['content_type']))) {
-      $this->importer->existing();
-      return parent::existing();
-    }
-    throw new FeedsNotExistingException(t('Source configuration not valid.'));
+    // Ensure that the source configuration is valid.
+    if (!$this->hasValidConfiguration()) {
+      throw new FeedsNotExistingException(t('Source configuration not valid.'));
+    }
+
+    // Ensure that the importer is persistent (= defined in code or DB).
+    $this->importer->existing();
+
+    // Ensure that the source is persistent (= defined in DB).
+    return parent::existing();
   }
 
   /**
diff --git a/tests/feeds_scheduler.test b/tests/feeds_scheduler.test
index 01c4393..fb605a8 100644
--- a/tests/feeds_scheduler.test
+++ b/tests/feeds_scheduler.test
@@ -25,7 +25,7 @@ class FeedsSchedulerTestCase extends FeedsWebTestCase {
     // Initialize scheduling.
     $init = $this->initSyndication();
 
-    // Disable syndication feed so cron doesn't import nodes
+    // Disable syndication feed so cron doesn't import nodes.
     $this->drupalLogin($this->admin_user);
     $edit = array(
       'syndication' => FALSE,