--- 1/src/java-config-2.sh.in
+++ 1/src/java-config-2.sh.in
@@ -9,13 +9,14 @@
 # See https://bugs.gentoo.org/show_bug.cgi?id=169925
 # for more details"
 
-if [ -z "${UID}" ] ; then
+if [ -z "${UID-}" ] ; then
 	# id lives in /usr/bin which might not be mounted
 	if type id >/dev/null 2>/dev/null ; then
 		user_id=$(id -u)
 	else
-		[ "${USER}" = "root" ] && user_id=0
+		[ "${USER-}" = "root" ] && user_id=0
 	fi
+else	user_id=${UID}
 fi
 
 # The root user uses the system vm
@@ -27,7 +28,7 @@
 fi
 
 # prepending to come before generation 1
-export MANPATH="${JAVA_HOME}/man:${MANPATH}"
-export JDK_HOME=${JAVA_HOME}
-export JAVAC=${JDK_HOME}/bin/javac
+export MANPATH="${JAVA_HOME}/man${MANPATH:+:}${MANPATH-}"
+export JDK_HOME="${JAVA_HOME}"
+export JAVAC="${JDK_HOME}/bin/javac"
 unset gentoo_user_vm gentoo_system_vm user_id