diff --git a/django/db/models/sql/aggregates.py b/django/db/models/sql/aggregates.py
index 6fdaf188c4..b7a38f5b69 100644
--- a/django/db/models/sql/aggregates.py
+++ b/django/db/models/sql/aggregates.py
@@ -21,6 +21,7 @@ class Aggregate(object):
     is_ordinal = False
     is_computed = False
     sql_template = '%(function)s(%(field)s)'
+    as_sql_takes_connection = True
 
     def __init__(self, col, source=None, is_summary=False, **extra):
         """Instantiate an SQL aggregate
@@ -72,15 +73,16 @@ class Aggregate(object):
         if isinstance(self.col, (list, tuple)):
             self.col = (change_map.get(self.col[0], self.col[0]), self.col[1])
 
-    def as_sql(self, quote_func=None):
+    def as_sql(self, qn, connection):
         "Return the aggregate, rendered as SQL."
-        if not quote_func:
-            quote_func = lambda x: x
 
         if hasattr(self.col, 'as_sql'):
-            field_name = self.col.as_sql(quote_func)
+            if getattr(self.col, 'as_sql_takes_connection', False):
+                field_name = self.col.as_sql(qn, connection)
+            else:
+                field_name = self.col.as_sql(qn)
         elif isinstance(self.col, (list, tuple)):
-            field_name = '.'.join([quote_func(c) for c in self.col])
+            field_name = '.'.join([qn(c) for c in self.col])
         else:
             field_name = self.col
 
@@ -127,4 +129,3 @@ class Variance(Aggregate):
     def __init__(self, col, sample=False, **extra):
         super(Variance, self).__init__(col, **extra)
         self.sql_function = sample and 'VAR_SAMP' or 'VAR_POP'
-
diff --git a/django/db/models/sql/expressions.py b/django/db/models/sql/expressions.py
index 2c447022d3..e0118fd198 100644
--- a/django/db/models/sql/expressions.py
+++ b/django/db/models/sql/expressions.py
@@ -78,6 +78,9 @@ class SQLEvaluator(object):
     def evaluate_leaf(self, node, qn, connection):
         col = self.cols[node]
         if hasattr(col, 'as_sql'):
-            return col.as_sql(qn), ()
+            if getattr(col, 'as_sql_takes_connection', False):
+                return col.as_sql(qn, connection), ()
+            else:
+                return col.as_sql(qn)
         else:
             return '%s.%s' % (qn(col[0]), qn(col[1])), ()
diff --git a/django/db/models/sql/query.py b/django/db/models/sql/query.py
index fb17db546a..f06a9c2300 100644
--- a/django/db/models/sql/query.py
+++ b/django/db/models/sql/query.py
@@ -746,7 +746,7 @@ class BaseQuery(object):
 
         result.extend([
             '%s%s' % (
-                aggregate.as_sql(quote_func=qn),
+                aggregate.as_sql(qn, self.connection),
                 alias is not None and ' AS %s' % qn(alias) or ''
             )
             for alias, aggregate in self.aggregate_select.items()
diff --git a/django/db/models/sql/subqueries.py b/django/db/models/sql/subqueries.py
index db514c8b75..8712a4fdac 100644
--- a/django/db/models/sql/subqueries.py
+++ b/django/db/models/sql/subqueries.py
@@ -421,17 +421,21 @@ class AggregateQuery(Query):
     An AggregateQuery takes another query as a parameter to the FROM
     clause and only selects the elements in the provided list.
     """
+    as_sql_takes_connection = True
+
     def add_subquery(self, query):
         self.subquery, self.sub_params = query.as_sql(with_col_aliases=True)
 
-    def as_sql(self, quote_func=None):
+    def as_sql(self, qn=None):
         """
         Creates the SQL for this query. Returns the SQL string and list of
         parameters.
         """
+        if qn is None:
+            qn = self.quote_name_unless_alias
         sql = ('SELECT %s FROM (%s) subquery' % (
             ', '.join([
-                aggregate.as_sql()
+                aggregate.as_sql(qn, self.connection)
                 for aggregate in self.aggregate_select.values()
             ]),
             self.subquery)
diff --git a/django/db/models/sql/where.py b/django/db/models/sql/where.py
index 69d798d3bb..ac9c375342 100644
--- a/django/db/models/sql/where.py
+++ b/django/db/models/sql/where.py
@@ -152,7 +152,11 @@ class WhereNode(tree.Node):
             field_sql = self.sql_for_columns(lvalue, qn, connection)
         else:
             # A smart object with an as_sql() method.
-            field_sql = lvalue.as_sql(quote_func=qn)
+            if getattr(lvalue, 'as_sql_takes_connection', False):
+                field_sql = lvalue.as_sql(qn, connection)
+            else:
+                field_sql = lvalue.as_sql(qn)
+
 
         if value_annot is datetime.datetime:
             cast_sql = connection.ops.datetime_cast_sql()