diff --git a/asyncpg/connect_utils.py b/asyncpg/connect_utils.py
index e215391b..092723a7 100644
--- a/asyncpg/connect_utils.py
+++ b/asyncpg/connect_utils.py
@@ -453,7 +453,7 @@ def _parse_connect_dsn_and_args(*, dsn, host, port, user,
                     server_settings = {**query, **server_settings}
 
         if connection_service_file is not None and service is not None:
-            pg_service = configparser.ConfigParser()
+            pg_service = configparser.ConfigParser(interpolation=None)
             pg_service.read(connection_service_file)
             if service in pg_service.sections():
                 service_params = pg_service[service]
diff --git a/tests/test_connect.py b/tests/test_connect.py
index 1c25d8d6..6aa34fb9 100644
--- a/tests/test_connect.py
+++ b/tests/test_connect.py
@@ -1286,7 +1286,7 @@ def test_connect_connection_service_file(self):
 host=somehost
 database=test_dbname
 user=admin
-password=test_password
+password=test%password
 target_session_attrs=primary
 krbsrvname=fakekrbsrvname
 gsslib=sspi
@@ -1322,7 +1322,7 @@ def test_connect_connection_service_file(self):
                     [('somehost', 5433)],
                     {
                         'user': 'admin',
-                        'password': 'test_password',
+                        'password': 'test%password',
                         'database': 'test_dbname',
                         'target_session_attrs': 'primary',
                         'krbsrvname': 'fakekrbsrvname',