diff --git a/django_remote_forms/forms.py b/django_remote_forms/forms.py
index e87e50e..ffa8bd0 100644
--- a/django_remote_forms/forms.py
+++ b/django_remote_forms/forms.py
@@ -196,9 +196,12 @@ def as_dict(self, validated=True):
 
         for field_name in file_fields:
             obj = form_dict['data'].get(field_name, None)
-            if getattr(obj, 'url', None):
-                form_dict['data'][field_name] = obj.url
-            else:
+            try:
+                if getattr(obj, 'url', None):
+                    form_dict['data'][field_name] = obj.url
+                else:
+                    form_dict['data'][field_name] = None
+            except ValueError:
                 form_dict['data'][field_name] = None
 
         return resolve_promise(form_dict)