diff --git a/tests/test_restrictions.py b/tests/test_restrictions.py
index 9ec90e66..0d6020f4 100644
--- a/tests/test_restrictions.py
+++ b/tests/test_restrictions.py
@@ -60,44 +60,37 @@ class RestrictionsTestCase(WithDataPortal, ZiplineTestCase):
             pd.Timedelta('1 minute'),
             pd.Timedelta('15 hours 5 minutes')
         ),
-        check_unordered=(False, True),
+        restriction_order=(
+            list(range(6)),      # Keep restrictions in order.
+            [0, 2, 1, 3, 5, 4],  # Re-order within asset.
+            [0, 3, 1, 4, 2, 5],  # Scramble assets, maintain per-asset order.
+            [0, 5, 2, 3, 1, 4],  # Scramble assets and per-asset order.
+        ),
         __fail_fast=True,
     )
-    def test_historical_restrictions(self, date_offset, check_unordered):
+    def test_historical_restrictions(self, date_offset, restriction_order):
         """
         Test historical restrictions for both interday and intraday
         restrictions, as well as restrictions defined in/not in order, for both
         single- and multi-asset queries
         """
-        if check_unordered:
-            def maybe_scramble(rs):
-                # Swap the first two restrictions to check that we don't care
-                # that the restriction dates are ordered.
-                tmp = rs[0]
-                rs[0] = rs[1]
-                rs[1] = tmp
-                return rs
-        else:
-            maybe_scramble = lambda r: r
-
         def rdate(s):
             """Convert a date string into a restriction for that date."""
             # Add date_offset to check that we handle intraday changes.
             return str_to_ts(s) + date_offset
 
-        all_restrictions = (
-            maybe_scramble([
-                Restriction(self.ASSET1, rdate('2011-01-04'), FROZEN),
-                Restriction(self.ASSET1, rdate('2011-01-05'), ALLOWED),
-                Restriction(self.ASSET1, rdate('2011-01-06'), FROZEN),
-            ])
-            +
-            maybe_scramble([
-                Restriction(self.ASSET2, rdate('2011-01-05'), FROZEN),
-                Restriction(self.ASSET2, rdate('2011-01-06'), ALLOWED),
-                Restriction(self.ASSET2, rdate('2011-01-07'), FROZEN),
-            ])
-        )
+        base_restrictions = [
+            Restriction(self.ASSET1, rdate('2011-01-04'), FROZEN),
+            Restriction(self.ASSET1, rdate('2011-01-05'), ALLOWED),
+            Restriction(self.ASSET1, rdate('2011-01-06'), FROZEN),
+            Restriction(self.ASSET2, rdate('2011-01-05'), FROZEN),
+            Restriction(self.ASSET2, rdate('2011-01-06'), ALLOWED),
+            Restriction(self.ASSET2, rdate('2011-01-07'), FROZEN),
+        ]
+        # Scramble the restrictions based on restriction_order to check that we
+        # don't depend on the order in which restrictions are provided to us.
+        all_restrictions = [base_restrictions[i] for i in restriction_order]
+
         restrictions_by_asset = groupby(lambda r: r.asset, all_restrictions)
 
         rl = HistoricalRestrictions(all_restrictions)
diff --git a/zipline/finance/asset_restrictions.py b/zipline/finance/asset_restrictions.py
index c22d5086..8724eae0 100644
--- a/zipline/finance/asset_restrictions.py
+++ b/zipline/finance/asset_restrictions.py
@@ -3,9 +3,9 @@ from numpy import vectorize
 from functools import partial, reduce
 import operator
 import pandas as pd
-from six import with_metaclass
+from six import with_metaclass, iteritems
 from collections import namedtuple
-from itertools import groupby
+from toolz import groupby
 
 from zipline.utils.enum import enum
 from zipline.utils.numpy_utils import vectorized_is_element
@@ -171,7 +171,7 @@ class HistoricalRestrictions(Restrictions):
                 restrictions_for_asset, key=lambda x: x.effective_date
             )
             for asset, restrictions_for_asset
-            in groupby(restrictions, lambda x: x.asset)
+            in iteritems(groupby(lambda x: x.asset, restrictions))
         }
 
     def is_restricted(self, assets, dt):