--- a/make/autoconf/spec.gmk.in	Tue Feb 06 16:04:46 2018 +0000
+++ b/make/autoconf/spec.gmk.in	Tue Feb 06 10:12:05 2018 -0800
@@ -737,6 +737,8 @@
 USE_EXTERNAL_LIBJPEG:=@USE_EXTERNAL_LIBJPEG@
 USE_EXTERNAL_LIBGIF:=@USE_EXTERNAL_LIBGIF@
 USE_EXTERNAL_LIBZ:=@USE_EXTERNAL_LIBZ@
+LIBZ_CFLAGS:=@LIBZ_CFLAGS@
+LIBZ_LIBS:=@LIBZ_LIBS@
 LIBZIP_CAN_USE_MMAP:=@LIBZIP_CAN_USE_MMAP@
 MSVCR_DLL:=@MSVCR_DLL@
 MSVCP_DLL:=@MSVCP_DLL@