diff --git a/squid-add-user.sh b/squid-add-user.sh
index 714a84c..da6f002 100644
--- a/squid-add-user.sh
+++ b/squid-add-user.sh
@@ -10,6 +10,11 @@
 # https://serverok.in/contact
 ############################################################
 
+if [ `whoami` != root ]; then
+	echo "ERROR: You need to run the script as user root or add sudo before command."
+	exit 1
+fi
+
 if [ ! -f /usr/bin/htpasswd ]; then
     echo "htpasswd not found"
     exit 1
diff --git a/squid-uninstall.sh b/squid-uninstall.sh
index 4ee0985..c221b63 100644
--- a/squid-uninstall.sh
+++ b/squid-uninstall.sh
@@ -10,6 +10,11 @@
 # https://serverok.in/contact
 ############################################################
 
+if [ `whoami` != root ]; then
+	echo "ERROR: You need to run the script as user root or add sudo before command."
+	exit 1
+fi
+
 if [ ! -f /usr/local/bin/sok-find-os ]; then
     echo "/usr/local/bin/sok-find-os not found"
     exit 1
diff --git a/squid3-install.sh b/squid3-install.sh
index 4f77a8f..f6fc447 100644
--- a/squid3-install.sh
+++ b/squid3-install.sh
@@ -10,6 +10,10 @@
 # https://serverok.in/contact
 ############################################################
 
+if [ `whoami` != root ]; then
+	echo "ERROR: You need to run the script as user root or add sudo before command."
+	exit 1
+fi
 
 /usr/bin/wget --no-check-certificate -O /usr/local/bin/sok-find-os https://raw.githubusercontent.com/serverok/squid-proxy-installer/master/sok-find-os.sh > /dev/null 2>&1
 chmod 755 /usr/local/bin/sok-find-os