diff --git a/xl2times/__main__.py b/xl2times/__main__.py
index 0feeb3c..a90b6dd 100644
--- a/xl2times/__main__.py
+++ b/xl2times/__main__.py
@@ -332,6 +332,7 @@ def produce_times_tables(
 def write_dd_files(
     tables: Dict[str, DataFrame], config: datatypes.Config, output_dir: str
 ):
+    encoding = "utf-8"
     os.makedirs(output_dir, exist_ok=True)
     for item in os.listdir(output_dir):
         if item.endswith(".dd"):
@@ -369,11 +370,13 @@ def convert_parameter(tablename: str, df: DataFrame):
     tables_in_file = {
         "ts.dd": ["ALL_TS"],
         "milestonyr.dd": ["MILESTONYR"],
-        "output.dd": [t for t in config.dd_table_order if t != "ALL_TS"],
+        "output.dd": [
+            t for t in config.dd_table_order if t not in ["ALL_TS", "MILESTONYR"]
+        ],
     }
 
     for fname, tablenames in tables_in_file.items():
-        with open(os.path.join(output_dir, fname), "w") as fout:
+        with open(os.path.join(output_dir, fname), "w", encoding=encoding) as fout:
             for tablename in [t for t in tablenames if t in tables]:
                 df = tables[tablename]
                 if tablename in sets: