diff --git a/src/mslice/plotting/globalfiguremanager.py b/src/mslice/plotting/globalfiguremanager.py
index 2d19aae6..fca1d067 100644
--- a/src/mslice/plotting/globalfiguremanager.py
+++ b/src/mslice/plotting/globalfiguremanager.py
@@ -186,6 +186,7 @@ def destroy_all(cls):
         }
         cls._activeQue = []
         cls._figures.clear()
+        cls.observers = []
 
     @classmethod
     def has_fignum(cls, num):
diff --git a/tests/app_test.py b/tests/app_test.py
index 347a3e61..64e8c42d 100644
--- a/tests/app_test.py
+++ b/tests/app_test.py
@@ -3,6 +3,7 @@
 import unittest
 from mock import patch
 from mslice.app.mainwindow import MainWindow
+from mslice.plotting.globalfiguremanager import GlobalFigureManager
 
 qapp = None
 
@@ -15,6 +16,8 @@ def setUp(self):
             qapp = QtWidgets.QApplication([' '])
 
     def tearDown(self):
+        GlobalFigureManager.destroy_all()
+
         # Required to sendPostedEvents twice to ensure the MainWindow is deleted
         qapp.sendPostedEvents()
         qapp.sendPostedEvents()