diff --git a/ipyparallel/serialize/serialize.py b/ipyparallel/serialize/serialize.py
index 327339bbf..60d860855 100644
--- a/ipyparallel/serialize/serialize.py
+++ b/ipyparallel/serialize/serialize.py
@@ -102,7 +102,12 @@ def serialize_object(obj, buffer_threshold=MAX_BYTES, item_threshold=MAX_ITEMS):
             buffers.extend(_extract_buffers(c, buffer_threshold))
     elif istype(obj, dict) and len(obj) < item_threshold:
         cobj = {}
-        for k in sorted(obj):
+        try:
+            keys = sorted(obj)
+        except TypeError:
+            # keys that can't be ordered (e.g. mixed str and int)
+            keys = list(obj)
+        for k in keys:
             c = can(obj[k])
             buffers.extend(_extract_buffers(c, buffer_threshold))
             cobj[k] = c
@@ -135,7 +140,9 @@ def deserialize_object(buffers, g=None):
         newobj = uncan_sequence(canned, g)
     elif istype(canned, dict) and len(canned) < MAX_ITEMS:
         newobj = {}
-        for k in sorted(canned):
+        # the unpickled dict keeps the key order serialize_object built it in,
+        # which is the order its buffers were extracted
+        for k in canned:
             c = canned[k]
             _restore_buffers(c, bufs)
             newobj[k] = uncan(c, g)
diff --git a/ipyparallel/tests/test_serialize.py b/ipyparallel/tests/test_serialize.py
index 46f614560..916b32405 100644
--- a/ipyparallel/tests/test_serialize.py
+++ b/ipyparallel/tests/test_serialize.py
@@ -148,6 +148,30 @@ def test_numpy_in_dict():
             assert_array_equal(A, B)
 
 
+def test_dict_unsortable_keys():
+    d = {'A': 1, 2: 2}
+    bufs = serialize_object(d)
+    d2, r = deserialize_object(bufs)
+    assert r == []
+    assert d2 == d
+
+
+def test_numpy_in_dict_unsortable_keys():
+    pytest.importorskip('numpy')
+    from numpy.testing import assert_array_equal
+
+    A = new_array((100, 100), dtype='float64')
+    B = new_array((1000,), dtype='int32')
+    d = {'b': B, 1: A, 'c': 3}
+    bufs = serialize_object(d)
+    assert len(bufs) == 3
+    d2, r = deserialize_object(bufs)
+    assert r == []
+    assert d2['c'] == 3
+    assert_array_equal(d2[1], A)
+    assert_array_equal(d2['b'], B)
+
+
 def test_class():
     @interactive
     class C: