--- a/langtools/make/build.properties	Wed Jul 05 21:42:16 2017 +0200
+++ b/langtools/make/build.properties	Mon May 16 12:03:41 2016 +0100
@@ -28,6 +28,10 @@
 javac.source = 9
 javac.target = 9
 
+#version used to compile build tools
+javac.build.source = 8
+javac.build.target = 8
+
 langtools.resource.includes = \
         com/sun/tools/javac/resources/compiler.properties