--- a/make/Images.gmk	Tue Feb 05 10:24:39 2019 +0100
+++ b/make/Images.gmk	Tue Feb 05 14:57:24 2019 +0100
@@ -144,7 +144,7 @@
       )
 
   ifeq ($(ZIP_EXTERNAL_DEBUG_SYMBOLS), true)
-    ifeq ($(OPENJDK_TARGET_OS), macosx)
+    ifeq ($(call isTargetOs, macosx), true)
       DEMO_FILES := $(call not-containing, .dSYM, $(DEMO_FILES))
     else
       DEMO_FILES := $(filter-out %.debuginfo %.pdb %.map, $(DEMO_FILES))
@@ -192,7 +192,7 @@
 ALL_JRE_MODULES := $(sort $(JRE_MODULES), $(foreach m, $(JRE_MODULES), \
     $(call FindTransitiveDepsForModule, $m)))
 
-ifeq ($(OPENJDK_TARGET_OS), windows)
+ifeq ($(call isTargetOs, windows), true)
   LIBS_TARGET_SUBDIR := bin
 else
   LIBS_TARGET_SUBDIR := lib
@@ -211,7 +211,7 @@
   DEBUGINFO_SUFFIXES := .debuginfo .pdb .map
   # On Macosx, if debug symbols have not been zipped, find all files inside *.dSYM
   # dirs.
-  ifeq ($(OPENJDK_TARGET_OS), macosx)
+  ifeq ($(call isTargetOs, macosx), true)
     $(eval $(call FillCacheFind, \
         $(SUPPORT_OUTPUTDIR)/modules_cmds $(SUPPORT_OUTPUTDIR)/modules_libs))
     FindDebuginfoFiles = \