diff --git a/django/db/models/sql/compiler.py b/django/db/models/sql/compiler.py
index fbb0152874..59b31dcb79 100644
--- a/django/db/models/sql/compiler.py
+++ b/django/db/models/sql/compiler.py
@@ -546,7 +546,7 @@ class SQLCompiler(object):
                 result.append('%s%s%s' % (connector, qn(name), alias_str))
             first = False
         for t in self.query.extra_tables:
-            alias, unused = self.query.table_alias(t)
+            alias, _ = self.query.table_alias(t)
             # Only add the alias if it's not already present (the table_alias()
             # calls increments the refcount, so an alias refcount of one means
             # this is the only reference.
diff --git a/django/db/models/sql/query.py b/django/db/models/sql/query.py
index 292322b9cb..ff86e8b45b 100644
--- a/django/db/models/sql/query.py
+++ b/django/db/models/sql/query.py
@@ -664,16 +664,16 @@ class Query(object):
         If 'create' is true, a new alias is always created. Otherwise, the
         most recently created alias for the table (if one exists) is reused.
         """
-        current = self.table_map.get(table_name)
-        if not create and current:
-            alias = current[0]
+        alias_list = self.table_map.get(table_name)
+        if not create and alias_list:
+            alias = alias_list[0]
             self.alias_refcount[alias] += 1
             return alias, False
 
         # Create a new alias for this table.
-        if current:
+        if alias_list:
             alias = '%s%d' % (self.alias_prefix, len(self.alias_map) + 1)
-            current.append(alias)
+            alias_list.append(alias)
         else:
             # The first occurrence of a table uses the table name directly.
             alias = table_name
@@ -900,7 +900,7 @@ class Query(object):
             return alias
 
         # No reuse is possible, so we need a new alias.
-        alias, _ = self.table_alias(table, True)
+        alias, _ = self.table_alias(table, create=True)
         if not lhs:
             # Not all tables need to be joined to anything. No join type
             # means the later columns are ignored.