--- a/jdk/make/test/JtregNative.gmk	Mon Jun 19 11:52:01 2017 +0200
+++ b/jdk/make/test/JtregNative.gmk	Wed Jun 21 21:50:13 2017 +0200
@@ -1,5 +1,5 @@
 #
-# Copyright (c) 2015, Oracle and/or its affiliates. All rights reserved.
+# Copyright (c) 2015, 2017, 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
@@ -35,12 +35,14 @@
 include MakeBase.gmk
 include TestFilesCompilation.gmk
 
+$(eval $(call IncludeCustomExtension, jdk, test/JtregNative.gmk))
+
 ################################################################################
 # Targets for building the native tests themselves.
 ################################################################################
 
 # Add more directories here when needed.
-BUILD_JDK_JTREG_NATIVE_SRC := \
+BUILD_JDK_JTREG_NATIVE_SRC += \
     $(JDK_TOPDIR)/test/native_sanity \
     $(JDK_TOPDIR)/test/java/lang/String/nativeEncoding \
     #