diff --git a/game/compat_1.9.nut b/game/compat_1.9.nut
new file mode 100644
--- /dev/null
+++ b/game/compat_1.9.nut
@@ -0,0 +1,15 @@
+/*
+ * This file is part of OpenTTD.
+ * OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
+ * OpenTTD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+ * See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+GSLog.Info("1.9 API compatibility in effect.");
+
+/* 1.11 adds a tile parameter. */
+GSCompany._ChangeBankBalance <- GSCompany.ChangeBankBalance;
+GSCompany.ChangeBankBalance <- function(company, delta, expenses_type)
+{
+	return GSCompany._ChangeBankBalance(company, delta, expenses_type, GSMap.TILE_INVALID);
+}