diff --git a/django/db/models/sql/datastructures.py b/django/db/models/sql/datastructures.py
index ab02f65042..9c3bb05e89 100644
--- a/django/db/models/sql/datastructures.py
+++ b/django/db/models/sql/datastructures.py
@@ -70,7 +70,7 @@ class Join:
         qn2 = connection.ops.quote_name
 
         # Add a join condition for each pair of joining columns.
-        for index, (lhs_col, rhs_col) in enumerate(self.join_cols):
+        for lhs_col, rhs_col in self.join_cols:
             join_conditions.append('%s.%s = %s.%s' % (
                 qn(self.parent_alias),
                 qn2(lhs_col),