diff --git a/xos/core/models/sliver.py b/xos/core/models/sliver.py
index 0e74b1d..e45152f 100644
--- a/xos/core/models/sliver.py
+++ b/xos/core/models/sliver.py
@@ -138,7 +138,7 @@
         return ", ".join(result)
     all_ips_string.short_description = "addresses"
 
-    def get_public_ip(self, sliver):
+    def get_public_ip(self):
         for ns in self.networkslivers.all():
             if (ns.ip) and (ns.network.template.visibility=="public") and (ns.network.template.translation=="none"):
                 return ns.ip
diff --git a/xos/hpc_observer/hpc_watcher.py b/xos/hpc_observer/hpc_watcher.py
index 16f1ef1..79d212e 100644
--- a/xos/hpc_observer/hpc_watcher.py
+++ b/xos/hpc_observer/hpc_watcher.py
@@ -126,7 +126,7 @@
         for sliver in slivers:
             sliver.has_error = False
 
-            ip = sliver.get_public_ip(sliver)
+            ip = sliver.get_public_ip()
             if not ip:
                 self.set_status(sliver, service, "watcher.DNS", "no public IP")
                 continue