diff --git a/plugins/FeedsProcessor.inc b/plugins/FeedsProcessor.inc
index 32a5719..e53adea 100755
--- a/plugins/FeedsProcessor.inc
+++ b/plugins/FeedsProcessor.inc
@@ -30,6 +30,11 @@ class FeedsAccessException extends Exception {}
 abstract class FeedsProcessor extends FeedsPlugin {
 
   /**
+   * Stores a cache of the serialized mappings.
+   */
+  protected $serialized_mappings = FALSE;
+
+  /**
    * Implements FeedsPlugin::pluginType().
    */
   public function pluginType() {
@@ -763,11 +768,10 @@ abstract class FeedsProcessor extends FeedsPlugin {
    *  Empty/NULL/FALSE strings return d41d8cd98f00b204e9800998ecf8427e
    */
   protected function hash($item) {
-    static $serialized_mappings;
-    if (!$serialized_mappings) {
-      $serialized_mappings = serialize($this->config['mappings']);
+    if ($this->serialized_mappings === FALSE) {
+      $this->serialized_mappings = serialize($this->config['mappings']);
     }
-    return hash('md5', serialize($item) . $serialized_mappings);
+    return hash('md5', serialize($item) . $this->serialized_mappings);
   }
 
   /**