diff --git a/wireguard-install.sh b/wireguard-install.sh
index 04826b3..3e7dd48 100644
--- a/wireguard-install.sh
+++ b/wireguard-install.sh
@@ -27,9 +27,27 @@ function addClient() {
 		exit 1
 	fi
 
-	read -rp "Client's WireGuard IPv4 " -e -i "${SERVER_WG_IPV4: : -1}2" CLIENT_WG_IPV4
+	until [[ "$IPV4_EXISTS" == '0' ]]; do
+		read -rp "Client's WireGuard IPv4 " -e -i "${SERVER_WG_IPV4: : -1}2" CLIENT_WG_IPV4
+		IPV4_EXISTS=$(grep -c "$CLIENT_WG_IPV4" "/etc/wireguard/$SERVER_WG_NIC.conf")
 
-	read -rp "Client's WireGuard IPv6 " -e -i "${SERVER_WG_IPV6: : -1}2" CLIENT_WG_IPV6
+		if [[ $IPV4_EXISTS == '1' ]]; then
+			echo ""
+			echo "A client with the specified IPv4 was already created, please choose another IPv4."
+			echo ""
+		fi
+	done
+
+	until [[ "$IPV6_EXISTS" == '0' ]]; do
+		read -rp "Client's WireGuard IPv6 " -e -i "${SERVER_WG_IPV6: : -1}2" CLIENT_WG_IPV6
+		IPV6_EXISTS=$(grep -c "$CLIENT_WG_IPV6" "/etc/wireguard/$SERVER_WG_NIC.conf")
+
+		if [[ $IPV6_EXISTS == '1' ]]; then
+			echo ""
+			echo "A client with the specified IPv6 was already created, please choose another IPv6."
+			echo ""
+		fi
+	done
 
 	# Adguard DNS by default
 	CLIENT_DNS_1="176.103.130.130"