diff --git a/src/Products/PluginIndexes/CompositeIndex/tests/testCompositeIndex.py b/src/Products/PluginIndexes/CompositeIndex/tests/testCompositeIndex.py
index d4d983b7..1675834a 100644
--- a/src/Products/PluginIndexes/CompositeIndex/tests/testCompositeIndex.py
+++ b/src/Products/PluginIndexes/CompositeIndex/tests/testCompositeIndex.py
@@ -285,7 +285,7 @@ def profileSearch(query, warmup=False, verbose=False):
                 # search must be roughly faster than default search
                 if res1 and res2:
                     self.assertLess(
-                        0.5 * duration2,
+                        0.4 * duration2,
                         duration1,
                         (duration2, duration1, query))
 
diff --git a/src/Products/PluginIndexes/unindex.py b/src/Products/PluginIndexes/unindex.py
index 9110bb0a..add32595 100644
--- a/src/Products/PluginIndexes/unindex.py
+++ b/src/Products/PluginIndexes/unindex.py
@@ -504,7 +504,12 @@ def query_index(self, record, resultset=None):
                 i_not_parm = self._apply_not(not_parm, resultset)
                 if i_not_parm:
                     return difference(resultset, i_not_parm)
-            record.keys = [k for k in index.keys() if k not in not_parm]
+            record.keys = list(index)
+            for parm in not_parm:
+                try:
+                    record.keys.remove(parm)
+                except ValueError:
+                    pass
         else:
             # convert query arguments into indexed format
             record.keys = list(map(self._convert, record.keys))