diff --git a/synapse/storage/engines/__init__.py b/synapse/storage/engines/__init__.py
index 035f9ea6e9..b3ab98c0fc 100644
--- a/synapse/storage/engines/__init__.py
+++ b/synapse/storage/engines/__init__.py
@@ -15,8 +15,6 @@
 import platform
 
 from ._base import BaseDatabaseEngine, IncorrectDatabaseSetup
-from .postgres import PostgresEngine
-from .sqlite import Sqlite3Engine
 
 
 def create_engine(database_config) -> BaseDatabaseEngine:
@@ -24,6 +22,7 @@ def create_engine(database_config) -> BaseDatabaseEngine:
 
     if name == "sqlite3":
         import sqlite3
+        from .sqlite import Sqlite3Engine
 
         return Sqlite3Engine(sqlite3, database_config)
 
@@ -34,6 +33,8 @@ def create_engine(database_config) -> BaseDatabaseEngine:
         else:
             import psycopg2  # type: ignore
 
+        from .postgres import PostgresEngine
+
         return PostgresEngine(psycopg2, database_config)
 
     raise RuntimeError("Unsupported database engine '%s'" % (name,))