--- a/make/test/BuildFailureHandler.gmk	Tue Feb 05 10:24:39 2019 +0100
+++ b/make/test/BuildFailureHandler.gmk	Tue Feb 05 14:57:24 2019 +0100
@@ -61,7 +61,7 @@
 
 ################################################################################
 
-ifeq ($(OPENJDK_TARGET_OS), windows)
+ifeq ($(call isTargetOs, windows), true)
 
   $(eval $(call SetupNativeCompilation, BUILD_LIBTIMEOUT_HANDLER, \
         NAME := timeoutHandler, \
@@ -99,7 +99,7 @@
 #
 RUN_DIR := $(FH_SUPPORT)/test
 # Add the dir of the dll to the path on windows
-ifeq ($(OPENJDK_TARGET_OS), windows)
+ifeq ($(call isTargetOs, windows), true)
   export PATH := $(PATH);$(FH_SUPPORT)
 endif