diff --git a/src/freedombone-installer b/src/freedombone-installer
index 850743546632177d4488b554f478eeb392cf28f8..bf5eee8cf1f7e4d5c0e26995706765e96e991569 100755
--- a/src/freedombone-installer
+++ b/src/freedombone-installer
@@ -1400,8 +1400,11 @@ function update_system_monitor {
         total_memory=$(free -m | grep "Mem:" | awk -F ' ' '{print $2}')
         used_memory_percent=$((used_memory * 100 / total_memory))
 
+        cpu_temperature=0
         cpu_temp=$(cat /sys/class/thermal/thermal_zone*/temp | head -n 1)
-        cpu_temperature=$((cpu_temp / 1000))
+        if [ "$cpu_temp" ]; then
+            cpu_temperature=$((cpu_temp / 1000))
+        fi
 
         local_hostname=$(grep 'host-name' /etc/avahi/avahi-daemon.conf | awk -F '=' '{print $2}').local
         webadmin_install_dir="/var/www/${local_hostname}/htdocs/admin"
diff --git a/src/freedombone-utils-webadmin b/src/freedombone-utils-webadmin
index 7b40cd85f67f73137cf71751aba1c52c28e8e884..ae9725feba55247c24b6251d5e36e1a8236ee86d 100755
--- a/src/freedombone-utils-webadmin
+++ b/src/freedombone-utils-webadmin
@@ -705,8 +705,11 @@ function webadmin_update_system_monitor {
     total_memory=$(free -m | grep "Mem:" | awk -F ' ' '{print $2}')
     used_memory_percent=$((used_memory * 100 / total_memory))
 
+    cpu_temperature=0
     cpu_temp=$(cat /sys/class/thermal/thermal_zone*/temp | head -n 1)
-    cpu_temperature=$((cpu_temp / 1000))
+    if [ "$cpu_temp" ]; then
+        cpu_temperature=$((cpu_temp / 1000))
+    fi
 
     local_hostname=$(grep 'host-name' /etc/avahi/avahi-daemon.conf | awk -F '=' '{print $2}').local
     webadmin_install_dir="/var/www/${local_hostname}/htdocs/admin"
diff --git a/webadmin/systemmonitor.php b/webadmin/systemmonitor.php
index 2840f74774a8f423b9241b13fce0fed14940db86..8459b98141ed643cf3ac870ae8dd5de146b78c68 100755
--- a/webadmin/systemmonitor.php
+++ b/webadmin/systemmonitor.php
@@ -5,7 +5,7 @@
 $output_filename = "settings.html";
 
 if (isset($_POST['submitsystemmonitor'])) {
-    $system_monitor_file = fopen(".system_monitor.txt", "w") or die("Unable to create setup file");
+    $system_monitor_file = fopen(".system_monitor.txt", "w") or die("Unable to create system monitor file");
     fwrite($system_monitor_file, " ");
     fclose($system_monitor_file);
     $output_filename = "system_monitor.html";