diff --git a/django/db/backends/postgresql/schema.py b/django/db/backends/postgresql/schema.py
index 321fa530aa..19f8b225e2 100644
--- a/django/db/backends/postgresql/schema.py
+++ b/django/db/backends/postgresql/schema.py
@@ -353,7 +353,7 @@ class DatabaseSchemaEditor(BaseDatabaseSchemaEditor):
         include=None,
         expressions=None,
     ):
-        sql = (
+        sql = sql or (
             self.sql_create_index
             if not concurrently
             else self.sql_create_index_concurrently