--- a/make/autoconf/spec.gmk.in	Tue Dec 05 23:11:27 2017 +0100
+++ b/make/autoconf/spec.gmk.in	Tue Dec 05 23:14:35 2017 +0100
@@ -565,6 +565,7 @@
 
 BUILD_JAVA_FLAGS := @BOOTCYCLE_JVM_ARGS_BIG@
 BUILD_JAVA=@FIXPATH@ $(BUILD_JDK)/bin/java $(BUILD_JAVA_FLAGS)
+BUILD_JAR=@FIXPATH@ $(BUILD_JDK)/bin/jar
 
 # Interim langtools and rmic modules and arguments
 INTERIM_LANGTOOLS_BASE_MODULES := java.compiler jdk.compiler jdk.javadoc