diff --git a/roles/bird/filter_plugins/bird.py b/roles/bird/filter_plugins/bird.py
index 2cf01de..5bfae8f 100644
--- a/roles/bird/filter_plugins/bird.py
+++ b/roles/bird/filter_plugins/bird.py
@@ -99,7 +99,7 @@ class IPFlag(str):
         pattern = r"(?P<ip>.*?)(?P<flag>[+-]|\{[0-9]+,[0-9]+\})?$"
         parts = re.match(pattern, v)
 
-        return (ip_network(parts.group("ip")), parts.group("flag"))
+        return (ip_network(parts.group("ip")), parts.group("flag") or "")
 
 
 class NetMatch(BaseModel):
@@ -245,7 +245,7 @@ def str_of_condition(condition: Condition, ctx: bool) -> str:
                     m for m in matches if isinstance(m[0], IPv6Network)
                 ]
 
-            return f"net ~ [ {', '.join([f'{network}{str(flag)}' for (network, flag) in networks])} ]"
+            return f"net ~ [ {', '.join([f'{network}{flag}' for (network, flag) in networks])} ]"
 
 
 def lines_of_action(action: Action, ctx: Context) -> Iterable[str]: