--- cygwin-service-installation-helper.sh.orig	2015-10-28 20:23:49.000000000 +1100
+++ cygwin-service-installation-helper.sh	2017-01-23 13:54:19.334891100 +1100
@@ -2882,7 +2882,8 @@
     if ! csih_use_file_etc "passwd"
     then
       # This test succeeds on domain member machines only, not on DCs.
-      if [ "\\\\${COMPUTERNAME,,*}" != "${LOGONSERVER,,*}" \
+      if [ -n "${LOGONSERVER}" \
+	   -a "\\\\${COMPUTERNAME,,*}" != "${LOGONSERVER,,*}" \
 	   -a "${LOGONSERVER}" != "\\\\MicrosoftAccount" ]
       then
 	# Lowercase of USERDOMAIN