diff --git a/src/functions/functions.ip-tunnel b/src/functions/functions.ip-tunnel
index 550b0b3..0a0c210 100644
--- a/src/functions/functions.ip-tunnel
+++ b/src/functions/functions.ip-tunnel
@@ -98,6 +98,24 @@ ip_tunnel_add() {
 		return ${EXIT_ERROR}
 	fi
 
+	# Detect the IP protocol, which is important to decide which mode we have to use
+	local remote_address_protocol="$(ip_detect_protocol "${remote_address}")"
+
+	# If we could not detect the IP protocol something with
+	# ${remote_address} is wrong
+	if ! isset remote_address_protocol; then
+		log ERROR "Could not determine remote address IP protocol"
+		return ${EXIT_ERROR}
+	fi
+
+	# We cannot mix IPv6 and IPv4
+	if [[ "${remote_address_protocol}" != \
+		"$(ip_detect_protocol "${local_address}")" ]] ; then
+		log ERROR "Local and remote address\
+			are not from the same IP protocol"
+		return ${EXIT_ERROR}
+	fi
+
 	# ikey and okey must be set for VTI devices
 	if [ "${mode}" = "vti" ] && (! isset ikey || ! isset okey); then
 		error "--ikey= and --okey= must be set for VTI device"