diff --git a/runbot_merge/controllers.py b/runbot_merge/controllers.py
index 2835742c..d8613ff8 100644
--- a/runbot_merge/controllers.py
+++ b/runbot_merge/controllers.py
@@ -62,7 +62,7 @@ def handle_pr(event):
     # is at event['change']['base']['ref'] (if the target changed), so edition
     # handling must occur before the rest of the steps
     if event['action'] == 'edited':
-        source = event['changes'].get('base', {'from': pr['base']})['from']['ref']
+        source = event['changes'].get('base', {'ref': {'from': b}})['ref']['from']
         source_branch = env['runbot_merge.branch'].search([
             ('name', '=', source),
             ('project_id', '=', repo.project_id.id),
diff --git a/runbot_merge/tests/fake_github/__init__.py b/runbot_merge/tests/fake_github/__init__.py
index 691b567e..1534d3de 100644
--- a/runbot_merge/tests/fake_github/__init__.py
+++ b/runbot_merge/tests/fake_github/__init__.py
@@ -492,7 +492,7 @@ class PR(Issue):
     def base(self, value):
         old, self._base = self._base, value
         self.repo.notify('pull_request', 'edited', self, {
-            'base': {'from': {'ref': old}}
+            'base': {'ref': {'from': old}}
         })
 
     def push(self, sha):