diff --git a/agent/nous_rate_guard.py b/agent/nous_rate_guard.py
index 415d367ca17b..0234eef2ea23 100644
--- a/agent/nous_rate_guard.py
+++ b/agent/nous_rate_guard.py
@@ -117,7 +117,7 @@ def record_nous_rate_limit(
         # Atomic write: write to temp file + rename
         fd, tmp_path = tempfile.mkstemp(dir=state_dir, suffix=".tmp")
         try:
-            with os.fdopen(fd, "w") as f:
+            with os.fdopen(fd, "w", encoding="utf-8") as f:
                 json.dump(state, f)
             atomic_replace(tmp_path, path)
         except Exception:
diff --git a/agent/shell_hooks.py b/agent/shell_hooks.py
index 3f155f20465c..f30125b45983 100644
--- a/agent/shell_hooks.py
+++ b/agent/shell_hooks.py
@@ -642,7 +642,7 @@ def save_allowlist(data: Dict[str, Any]) -> None:
             prefix=f"{p.name}.", suffix=".tmp", dir=str(p.parent),
         )
         try:
-            with os.fdopen(fd, "w") as fh:
+            with os.fdopen(fd, "w", encoding="utf-8") as fh:
                 fh.write(json.dumps(data, indent=2, sort_keys=True))
             atomic_replace(tmp_path, p)
         except Exception: