diff --git a/update-firewall-source.py b/update-firewall-source.py
index ee1406d..b4f0773 100644
--- a/update-firewall-source.py
+++ b/update-firewall-source.py
@@ -296,6 +296,10 @@ def add_rule_elem(
 
     global arg_fw_rule_data
 
+    if arg_proto == "icmpv6" and address_family == "ipv4":
+        arg_proto = "icmp"
+    if arg_proto == "icmp" and address_family == "ipv6":
+        arg_proto = "icmpv6"
     try:
         lxml.etree.SubElement(arg_fw_rule_data, "rule",
                               ipv=f"{address_family}",