diff --git a/src/lightdm-webkit2-greeter-ext.c b/src/lightdm-webkit2-greeter-ext.c
index 96d5348..7dcae64 100644
--- a/src/lightdm-webkit2-greeter-ext.c
+++ b/src/lightdm-webkit2-greeter-ext.c
@@ -1022,7 +1022,7 @@ static const JSStaticValue lightdm_greeter_values[] = {
 	{"layout",              get_layout_cb,              set_layout_cb, kJSPropertyAttributeNone},
 	{"sessions",            get_sessions_cb,            NULL,          kJSPropertyAttributeReadOnly},
 	{"num_users",           get_num_users_cb,           NULL,          kJSPropertyAttributeReadOnly},
-	{"default_session",     get_default_session_cb,     NULL,          kJSPropertyAttributeNone},
+	{"default_session",     get_default_session_cb,     NULL,          kJSPropertyAttributeReadOnly},
 	{"timed_login_user",    get_timed_login_user_cb,    NULL,          kJSPropertyAttributeReadOnly},
 	{"timed_login_delay",   get_timed_login_delay_cb,   NULL,          kJSPropertyAttributeReadOnly},
 	{"authentication_user", get_authentication_user_cb, NULL,          kJSPropertyAttributeReadOnly},