diff --git a/backtest.py b/backtest.py
index 0299028..4874a6c 100644
--- a/backtest.py
+++ b/backtest.py
@@ -694,7 +694,7 @@ def main() -> int:
     df.to_csv(out_dir / "trades.csv", index=False)
 
     summary = summarize(df)
-    (out_dir / "summary.txt").write_text(summary)
+    (out_dir / "summary.txt").write_text(summary, encoding="utf-8")
 
     print("\n" + summary)
     print(f"\n📁 trades.csv  → {out_dir/'trades.csv'}")