diff --git a/IPython/zmq/zmqshell.py b/IPython/zmq/zmqshell.py
index 04ee838..5a5f955 100644
--- a/IPython/zmq/zmqshell.py
+++ b/IPython/zmq/zmqshell.py
@@ -33,7 +33,7 @@ from IPython.utils import io
 from IPython.utils.path import get_py_filename
 from IPython.utils.traitlets import Instance, Type, Dict
 from IPython.utils.warn import warn
-from IPython.zmq.displayhook import ZMQShellDisplayHook
+from IPython.zmq.displayhook import ZMQShellDisplayHook, _encode_png
 from IPython.zmq.session import extract_header
 from session import Session