diff --git a/app/Ninja/Transformers/EntityTransformer.php b/app/Ninja/Transformers/EntityTransformer.php
index 4be378e72fc2..3e299554a479 100644
--- a/app/Ninja/Transformers/EntityTransformer.php
+++ b/app/Ninja/Transformers/EntityTransformer.php
@@ -37,7 +37,13 @@ class EntityTransformer extends TransformerAbstract
 
     protected function getTimestamp($date)
     {
-        return method_exists($date, 'getTimestamp') ? $date->getTimestamp() : null;
+        if (method_exists($date, 'getTimestamp')) {
+            return $date->getTimestamp();
+        } elseif (is_string($date)) {
+            return strtotime($date);
+        } else {
+            return null;
+        }
     }
 
     public function getDefaultIncludes()