diff --git a/tools/install-built-ports.sh b/tools/install-built-ports.sh
index 0f8a1758..01e4f225 100755
--- a/tools/install-built-ports.sh
+++ b/tools/install-built-ports.sh
@@ -6,6 +6,24 @@ source $(dirname $0)/env.sh
 
 cd $LUNA_ROOT/ports
 
+unset_vars()
+{
+    unset pkgname
+    unset pkgver
+    unset pkgurl
+    unset pkgmode
+    unset setupdir
+    unset builddir
+    unset installdir
+    unset srcdir
+    unset port_unpack
+    unset port_patch
+    unset port_configure
+    unset port_build
+    unset port_install
+    unset port_uninstall
+}
+
 if ! [ -f ./ports.list ]
 then
     echo "No ports built."
@@ -13,6 +31,9 @@ fi
 
 install_port()
 {
+    unset_vars
+    cd $LUNA_ROOT/ports
+    export DESTDIR=${DESTDIR:-"$LUNA_ROOT/initrd"}
     export portdir=$PWD/$1
     export workdir=$portdir/workdir
     source $portdir/package.sh