diff --git a/IPython/zmq/tests/test_serialize.py b/IPython/zmq/tests/test_serialize.py
index 2a1a33a..c632164 100644
--- a/IPython/zmq/tests/test_serialize.py
+++ b/IPython/zmq/tests/test_serialize.py
@@ -87,7 +87,7 @@ def _scrub_nan(A):
         for field in A.dtype.fields.keys():
             try:
                 A[field][numpy.isnan(A[field])] = 0
-            except TypeError:
+            except (TypeError, NotImplementedError):
                 # e.g. str dtype
                 pass