diff --git a/exporter.py b/exporter.py
index cd9229c..d9fc8e3 100644
--- a/exporter.py
+++ b/exporter.py
@@ -22,14 +22,17 @@ _IMPL_PATH = (
 
 
 def _load_impl():
+    module_name = __name__ if __name__ != "__main__" else "_xtb_wealthfolio_exporter_impl"
     script_dir = _IMPL_PATH.parent
     if str(script_dir) not in sys.path:
         sys.path.insert(0, str(script_dir))
-    spec = importlib.util.spec_from_file_location(__name__, _IMPL_PATH)
+    spec = importlib.util.spec_from_file_location(module_name, _IMPL_PATH)
     if spec is None or spec.loader is None:
         raise ImportError(f"Could not load XTB Wealthfolio implementation at {_IMPL_PATH}")
     module = importlib.util.module_from_spec(spec)
-    sys.modules[__name__] = module
+    sys.modules[module_name] = module
+    if __name__ != "__main__":
+        sys.modules[__name__] = module
     spec.loader.exec_module(module)
     return module
 
diff --git a/skills/xtb-portfolio-review/scripts/main.py b/skills/xtb-portfolio-review/scripts/main.py
index 6d08a49..f9bef3c 100644
--- a/skills/xtb-portfolio-review/scripts/main.py
+++ b/skills/xtb-portfolio-review/scripts/main.py
@@ -2,6 +2,7 @@ import argparse
 import contextlib
 import io
 import re
+import warnings
 from dataclasses import dataclass, field
 from datetime import datetime, date, timedelta
 from html import escape
@@ -37,6 +38,18 @@ COST_FALLBACK_NOTES = {
     ),
 }
 
+
+def suppress_openpyxl_default_style_warning() -> None:
+    warnings.filterwarnings(
+        "ignore",
+        message=r"Workbook contains no default style, apply openpyxl's default",
+        category=UserWarning,
+        module=r"openpyxl\.styles\.stylesheet",
+    )
+
+
+suppress_openpyxl_default_style_warning()
+
 # XTB "Type" values that represent trading activity (not cash transfers).
 TRADE_TYPE_RE = re.compile(
     r"stock\s*(purchase|sale|buy|sell)|\bopen\b|\bclose\b",
diff --git a/skills/xtb-wealthfolio-export/scripts/main.py b/skills/xtb-wealthfolio-export/scripts/main.py
index ba4699a..0ddd29e 100644
--- a/skills/xtb-wealthfolio-export/scripts/main.py
+++ b/skills/xtb-wealthfolio-export/scripts/main.py
@@ -2,6 +2,7 @@ import argparse
 import contextlib
 import io
 import re
+import warnings
 from dataclasses import dataclass, field
 from datetime import datetime, date, timedelta
 from html import escape
@@ -37,6 +38,18 @@ COST_FALLBACK_NOTES = {
     ),
 }
 
+
+def suppress_openpyxl_default_style_warning() -> None:
+    warnings.filterwarnings(
+        "ignore",
+        message=r"Workbook contains no default style, apply openpyxl's default",
+        category=UserWarning,
+        module=r"openpyxl\.styles\.stylesheet",
+    )
+
+
+suppress_openpyxl_default_style_warning()
+
 # XTB "Type" values that represent trading activity (not cash transfers).
 TRADE_TYPE_RE = re.compile(
     r"stock\s*(purchase|sale|buy|sell)|\bopen\b|\bclose\b",
diff --git a/test_portfolio.py b/test_portfolio.py
index 895b706..e92b7b2 100644
--- a/test_portfolio.py
+++ b/test_portfolio.py
@@ -1,3 +1,5 @@
+import warnings
+
 import pandas as pd
 import pytest
 
@@ -44,6 +46,27 @@ def cash_row(type_, instrument, amount, comment="", time="2026-01-15 10:00:00"):
 # Generic helpers
 # ---------------------------------------------------------------------------
 class TestHelpers:
+    def test_suppresses_openpyxl_default_style_warning_only(self):
+        with warnings.catch_warnings(record=True) as caught:
+            warnings.simplefilter("default")
+            main.suppress_openpyxl_default_style_warning()
+            warnings.warn_explicit(
+                "Workbook contains no default style, apply openpyxl's default",
+                UserWarning,
+                "stylesheet.py",
+                237,
+                module="openpyxl.styles.stylesheet",
+            )
+            warnings.warn_explicit(
+                "Another workbook warning",
+                UserWarning,
+                "stylesheet.py",
+                237,
+                module="openpyxl.styles.stylesheet",
+            )
+
+        assert [str(w.message) for w in caught] == ["Another workbook warning"]
+
     def test_clean_columns_normalizes(self):
         df = pd.DataFrame(columns=["Open Price", "Profit/Loss", "  Ticker  "])
         out = clean_columns(df)