diff --git a/backend/src/api/nft_manager.py b/backend/src/api/nft_manager.py
index 8633bda..72b4c61 100644
--- a/backend/src/api/nft_manager.py
+++ b/backend/src/api/nft_manager.py
@@ -62,9 +62,9 @@ class NftManager:
         Raises NftError on failure or when output cannot be parsed as JSON.
         """
         res = self.nft.json_cmd("list ruleset")
-        if res["rc"] != 0:
-            raise NftError(f"nft list ruleset failed: {res['stderr']}")
-        return res["stdout"]
+        if res[0] != 0:
+            raise NftError(f"nft list ruleset failed: {res[2]}")
+        return res[1]
 
     def list_chain_text(self, family: str, table: str, chain: str) -> str:
         """