diff --git a/Orange/classification/majority.py b/Orange/classification/majority.py
index 212f38b8b0b..0a7f8ba426c 100644
--- a/Orange/classification/majority.py
+++ b/Orange/classification/majority.py
@@ -33,7 +33,8 @@ def fit_storage(self, dat):
         probs = np.array(dist)
         ties = np.flatnonzero(probs == probs.max())
         if len(ties) > 1:
-            random_idx = int(sha1(bytes(dat.Y)).hexdigest(), 16) % len(ties)
+            random_idx = int(sha1(np.ascontiguousarray(dat.Y).data)
+                             .hexdigest(), 16) % len(ties)
             unif_maj = ties[random_idx]
         else:
             unif_maj = None
diff --git a/Orange/classification/rules.py b/Orange/classification/rules.py
index 189f0698f73..52a7f068919 100644
--- a/Orange/classification/rules.py
+++ b/Orange/classification/rules.py
@@ -149,7 +149,8 @@ def hash_dist(x):
     hash : int
         Hash function result.
     """
-    return int(sha1(bytes(x)).hexdigest(), base=16) & 0xffffffff
+    return int(sha1(np.ascontiguousarray(x).data)
+               .hexdigest(), base=16) & 0xffffffff
 
 
 class Evaluator:
diff --git a/Orange/tests/test_preprocess.py b/Orange/tests/test_preprocess.py
index 8112e72a34d..60f10120f02 100644
--- a/Orange/tests/test_preprocess.py
+++ b/Orange/tests/test_preprocess.py
@@ -50,7 +50,11 @@ def test_refuse_data_in_constructor(self):
             self.assertTrue(os.environ.get('ORANGE_DEPRECATIONS_ERROR'))
         expected = self.assertRaises if is_CI else self.assertWarns
         with expected(OrangeDeprecationWarning):
-            Orange.preprocess.preprocess.Preprocess(Table('iris'))
+            try:
+                Orange.preprocess.preprocess.Preprocess(Table('iris'))
+            except NotImplementedError:
+                # Expected from default Preprocess.__call__
+                pass
 
 
 class RemoveConstant(unittest.TestCase):