diff --git a/src/bitmessageqt/__init__.py b/src/bitmessageqt/__init__.py
index 4cdcae30..04562fe6 100644
--- a/src/bitmessageqt/__init__.py
+++ b/src/bitmessageqt/__init__.py
@@ -2721,6 +2721,8 @@ class MyForm(settingsmixin.SMainWindow):
                 waitForSync = True
             elif reply == QtGui.QMessageBox.Cancel:
                 return
+            else:
+                Missing().stop()
 
         if shared.statusIconColor == 'red':
             reply = QtGui.QMessageBox.question(self, _translate("MainWindow", "Not connected"),
diff --git a/src/inventory.py b/src/inventory.py
index 77291a5c..0e81e756 100644
--- a/src/inventory.py
+++ b/src/inventory.py
@@ -90,8 +90,11 @@ class Missing(object):
         super(self.__class__, self).__init__()
         self.lock = RLock()
         self.hashes = {}
+        self.stopped = False
 
     def add(self, objectHash):
+        if self.stopped:
+            return
         with self.lock:
             if not objectHash in self.hashes:
                 self.hashes[objectHash] = {'peers':[], 'requested':0}
@@ -105,6 +108,8 @@ class Missing(object):
         with self.lock:
             try:
                 self.hashes[objectHash]['peers'].remove(current_thread().peer)
+            except KeyError:
+                return
             except ValueError:
                 pass
             if len(self.hashes[objectHash]['peers']) == 0:
@@ -131,6 +136,10 @@ class Missing(object):
             if objectHash in self.hashes:
                 del self.hashes[objectHash]
 
+    def stop(self):
+        with self.lock:
+            self.hashes = {}
+
     def threadEnd(self):
         with self.lock:
             for objectHash in self.hashes: