--- old/make/gendata/GendataTZDB.gmk	2020-03-23 19:56:28.383962763 +0100
+++ new/make/gendata/GendataTZDB.gmk	2020-03-23 19:56:28.047962765 +0100
@@ -1,5 +1,5 @@
 #
-# Copyright (c) 2012, 2018, Oracle and/or its affiliates. All rights reserved.
+# Copyright (c) 2012, 2020, Oracle and/or its affiliates. All rights reserved.
 # DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 #
 # This code is free software; you can redistribute it and/or modify it
@@ -25,6 +25,8 @@
 
 GENDATA_TZDB :=
 
+TOOL_TZDB = $(JAVA_SMALL) -cp $(BUILDTOOLS_OUTPUTDIR)/jdk_tools_classes \
+    org.openjdk.buildtools.tzdb.TzdbZoneRulesCompiler
 #
 # Time zone data file creation
 #