diff --git a/build.sdcard/raspbianStretchDesktop.sh b/build.sdcard/raspbianStretchDesktop.sh
index ebf4498..a86539e 100644
--- a/build.sdcard/raspbianStretchDesktop.sh
+++ b/build.sdcard/raspbianStretchDesktop.sh
@@ -444,6 +444,14 @@ sudo chmod +x /home/admin/_bootstrap.sh
 sudo cp ./assets/bootstrap.service /etc/systemd/system/bootstrap.service
 sudo systemctl enable bootstrap
 
+# *** BOOTSTRAP ***
+# see background README for details
+echo ""
+echo "*** RASPI BACKGROUND SERVICE ***"
+sudo chmod +x /home/admin/_background.sh
+sudo cp ./assets/background.service /etc/systemd/system/background.service
+sudo systemctl enable background
+
 # *** RASPIBLITZ IMAGE READY ***
 echo ""
 echo "**********************************************"
diff --git a/home.admin/_background.sh b/home.admin/_background.sh
index 86f014c..15295fa 100644
--- a/home.admin/_background.sh
+++ b/home.admin/_background.sh
@@ -34,8 +34,8 @@ do
   ####################################################
 
   # every 5 minutes
-  triggerRecheckDHCP=$(((counter % 300)+1))
-  if [ triggerRecheckDHCP -eq 1 ]; then
+  recheckDHCP=$((($counter % 300)+1))
+  if [ "recheckDHCP" -eq 1 ]; then
     echo "*** RECHECK DHCP-SERVER  ***"
 
     # get the local network IP
@@ -59,7 +59,7 @@ do
 
   # every 15min - not too often
   # because its a ping to external service
-  recheckPublicIP=$(((counter % 60)+1))
+  recheckPublicIP=$((($counter % 60)+1))
   if [ recheckPublicIP -eq 1 ]; then
     echo "*** RECHECK PUBLIC IP ***"