diff --git a/IPython/core/tests/test_displayhook.py b/IPython/core/tests/test_displayhook.py
index a00357b..12f4a8d 100644
--- a/IPython/core/tests/test_displayhook.py
+++ b/IPython/core/tests/test_displayhook.py
@@ -1,4 +1,7 @@
+import sys
 from IPython.testing.tools import AssertPrints, AssertNotPrints
+from IPython.core.displayhook import CapturingDisplayHook
+from IPython.utils.capture import CapturedIO
 
 ip = get_ipython()