diff --git a/dynamic_rest/processors.py b/dynamic_rest/processors.py
index 4fec4c98..44dcd12f 100644
--- a/dynamic_rest/processors.py
+++ b/dynamic_rest/processors.py
@@ -120,7 +120,7 @@ def process(self, obj, parent=None, parent_key=None, depth=0):
                     self.data[name].append(obj)
                 else:
                     # obj sideloaded, but maybe with other fields
-                    for o in self.data[name]:
+                    for o in self.data.get(name, []):
                         if o.instance.pk == pk:
                             o.update(obj)
                             break