diff --git a/zuul/model.py b/zuul/model.py
index 904e8f3516..d6fc1f02d7 100644
--- a/zuul/model.py
+++ b/zuul/model.py
@@ -412,12 +412,13 @@ class ChangeQueue(object):
             self._jobs |= set(self.pipeline.getJobTree(project).getJobs())
 
     def enqueueChange(self, change):
-        item = QueueItem(self, self.pipeline, change)
+        item = QueueItem(self.pipeline, change)
         self.enqueueItem(item)
         item.enqueue_time = time.time()
         return item
 
     def enqueueItem(self, item):
+        item.pipeline = self.pipeline
         if self.dependent and self.queue:
             item.item_ahead = self.queue[-1]
             item.item_ahead.items_behind.append(item)
@@ -659,8 +660,7 @@ class BuildSet(object):
 class QueueItem(object):
     """A changish inside of a Pipeline queue"""
 
-    def __init__(self, change_queue, pipeline, change):
-        self.change_queue = change_queue
+    def __init__(self, pipeline, change):
         self.pipeline = pipeline
         self.change = change  # a changeish
         self.build_sets = []
diff --git a/zuul/scheduler.py b/zuul/scheduler.py
index 7ca1e35cb2..5a085e23e6 100644
--- a/zuul/scheduler.py
+++ b/zuul/scheduler.py
@@ -1255,19 +1255,18 @@ class BasePipelineManager(object):
                                                         item.change.branch)
             self.log.info("Reported change %s status: all-succeeded: %s, "
                           "merged: %s" % (item.change, succeeded, merged))
+            change_queue = self.pipeline.getQueue(item.change.project)
             if not (succeeded and merged):
                 self.log.debug("Reported change %s failed tests or failed "
                                "to merge" % (item.change))
-                item.change_queue.decreaseWindowSize()
+                change_queue.decreaseWindowSize()
                 self.log.debug("%s window size decreased to %s" %
-                               (item.change_queue,
-                                item.change_queue.window))
+                               (change_queue, change_queue.window))
                 raise MergeFailure("Change %s failed to merge" % item.change)
             else:
-                item.change_queue.increaseWindowSize()
+                change_queue.increaseWindowSize()
                 self.log.debug("%s window size increased to %s" %
-                               (item.change_queue,
-                                item.change_queue.window))
+                               (change_queue, change_queue.window))
 
     def _reportItem(self, item):
         if item.reported: