diff --git a/extra/modules/bodiffusion.ptl b/extra/modules/bodiffusion.ptl
index de6710b..777756e 100644
--- a/extra/modules/bodiffusion.ptl
+++ b/extra/modules/bodiffusion.ptl
@@ -84,7 +84,7 @@ class AccessCodeMailer:
     def __call__(self, job=None):
         count = 0
         for user in User.select():
-            for role_id in self.objectdef.roles:
+            for role_id in (self.objectdef.roles or []):
                 if role_id in (user.roles or []):
                     break
             else:
@@ -144,7 +144,7 @@ class ParticipantsMailer:
                     user_ids[object.user_id] = True
 
         for user in User.select():
-            for role_id in self.objectdef.roles:
+            for role_id in (self.objectdef.roles or []):
                 if role_id in (user.roles or []):
                     break
             else:
@@ -349,7 +349,7 @@ class DiffusionDirectory(Directory):
         search_result = False
 
         user_ids = Set()
-        for role_id in self.objectdef.roles:
+        for role_id in (self.objectdef.roles or []):
             try:
                 user_ids_with_role = User.get_ids_with_indexed_value(
                                 'roles', role_id, auto_fallback=False)
@@ -388,7 +388,7 @@ class DiffusionDirectory(Directory):
                      user_ids = Set()
                      for user_key in keys:
                          user = User.get(user_key)
-                         for role_id in self.objectdef.roles:
+                         for role_id in (self.objectdef.roles or []):
                              if role_id in (user.roles or []):
                                  break
                          else:
@@ -482,7 +482,7 @@ class DiffusionDirectory(Directory):
         if not user_id:
             return redirect('.')
         user = User.get(user_id)
-        for role_id in self.objectdef.roles:
+        for role_id in (self.objectdef.roles or []):
             if role_id in user.roles:
                 user.roles.remove(role_id)
         if not user.roles:
@@ -528,7 +528,7 @@ class DiffusionDirectory(Directory):
 
         user.name = name
 
-        for role_id in self.objectdef.roles:
+        for role_id in (self.objectdef.roles or []):
             if not role_id in user.roles:
                 user.roles.append(role_id)
 
@@ -599,7 +599,7 @@ class DiffusionDirectory(Directory):
                         user.email = email
                     if len(line) == 2:
                         user.name = line[1]
-                    for role_id in self.objectdef.roles:
+                    for role_id in (self.objectdef.roles or []):
                         if not role_id in user.roles:
                             user.roles.append(role_id)
                     user.store()
@@ -778,7 +778,7 @@ class DiffusionDirectory(Directory):
                         # this user doesn't exist
                         continue
                     touched = False
-                    for role_id in self.objectdef.roles:
+                    for role_id in (self.objectdef.roles or []):
                         if role_id in user.roles:
                             user.roles.remove(role_id)
                             touched = True