diff --git a/cacheops/getset.py b/cacheops/getset.py
index d6c567ac..e7d127e7 100644
--- a/cacheops/getset.py
+++ b/cacheops/getset.py
@@ -142,5 +142,5 @@ def _conj_cache_key(table, conj):
                                          for conj in disj]
 
 def dnfs_to_schemes(cond_dnfs):
-    return {table: [",".join(sorted(conj)) for conj in disj]
+    return {table: list({",".join(sorted(conj)) for conj in disj})
             for table, disj in cond_dnfs.items() if disj}
diff --git a/tests/tests.py b/tests/tests.py
index c5ffd7b5..58127d32 100644
--- a/tests/tests.py
+++ b/tests/tests.py
@@ -1,4 +1,6 @@
 from contextlib import contextmanager
+from functools import reduce
+import operator
 import re
 import platform
 import unittest
@@ -718,6 +720,19 @@ def test_430_no_error_raises(self):
         # no error raises on delete
         media_type.delete()
 
+    def test_480(self):
+        orm_lookups = ['title__icontains', 'category__title__icontains', ]
+        search_terms = ['1', "2", "3", "4", "5", "6", "7", "8", "9", "10", "11", "12", "13"]
+        queryset = Post.objects.filter(visible=True)
+        conditions = []
+        for search_term in search_terms:
+            queries = [
+                models.Q(**{orm_lookup: search_term})
+                for orm_lookup in orm_lookups
+            ]
+            conditions.append(reduce(operator.or_, queries))
+        list(queryset.filter(reduce(operator.and_, conditions)).cache())
+
 
 class RelatedTests(BaseTestCase):
     fixtures = ['basic']