diff --git a/includes/entity.inc b/includes/entity.inc
index 8cf0418..ede5740 100644
--- a/includes/entity.inc
+++ b/includes/entity.inc
@@ -41,7 +41,9 @@ class Entity {
 
     // Set initial values.
     foreach ($values as $key => $value) {
-      $this->$key = $value;
+      if (!isset($this->$key)) {
+        $this->$key = $value;
+      }
     }
   }