diff -r e30211561a17 -r 48ff68e2fe5c make/lib/Lib-jdk.attach.gmk
--- a/make/lib/Lib-jdk.attach.gmk	Thu Feb 07 10:26:32 2019 +0100
+++ b/make/lib/Lib-jdk.attach.gmk	Thu Feb 07 12:35:45 2019 +0100
@@ -27,7 +27,7 @@
 
 ################################################################################
 
-ifeq ($(OPENJDK_TARGET_OS), windows)
+ifeq ($(call isTargetOs, windows), true)
   # In (at least) VS2013 and later, -DPSAPI_VERSION=1 is needed to generate
   # a binary that is compatible with windows versions older than 7/2008R2.
   # See MSDN documentation for GetProcessMemoryInfo for more information.