diff --git a/ckanext/validation/plugin/__init__.py b/ckanext/validation/plugin/__init__.py
index d648709e..f9018174 100644
--- a/ckanext/validation/plugin/__init__.py
+++ b/ckanext/validation/plugin/__init__.py
@@ -225,7 +225,10 @@ def before_update(self, context, current_resource, updated_resource):
         needs_validation = False
         if ((
             # New file uploaded
-            updated_resource.get(u'upload') or
+            (updated_resource.get(u'upload') or
+             (isinstance(updated_resource.get(u'upload'), cgi.FieldStorage) and  # workaround falsy cgi.FieldStorage bug: https://bugs.python.org/issue19097
+              (getattr(updated_resource.get(u'upload'), 'file', False) or
+               getattr(updated_resource.get(u'upload'), 'filename', False)))) or
             # External URL changed
             updated_resource.get(u'url') != current_resource.get(u'url') or
             # Schema changed