diff --git a/pandora/archive/models.py b/pandora/archive/models.py
index a3d79e5..95610e0 100644
--- a/pandora/archive/models.py
+++ b/pandora/archive/models.py
@@ -253,6 +253,8 @@ class File(models.Model):
         return False
 
     def json(self, keys=None, user=None):
+        if keys and not 'instances' in keys:
+            keys.append('instances')
         resolution = (self.width, self.height)
         if resolution == (0, 0):
             resolution = None