diff --git a/CLAUDE.md b/CLAUDE.md
index 7df6cf8..f71299e 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -147,6 +147,10 @@ get_language()                              # → "vi"
 
 Minimum is Python **3.9**. All files that use `X | Y` union type annotations **must** have `from __future__ import annotations` as the first import. Without it, the `|` syntax raises `TypeError` at runtime on Python < 3.10. Every module in `arma_modlist_tools/` already has it; any new CLI script you add must include it too.
 
+### `fix_console_encoding` — `None` stdout guard
+
+When the GUI is launched via `pythonw.exe` (no console window), Python sets `sys.stdout` and `sys.stderr` to `None`. `fix_console_encoding()` must check `if sys.stdout is None or sys.stderr is None: return` **before** accessing `.encoding`, otherwise it raises `AttributeError: 'NoneType' object has no attribute 'encoding'`. This error surfaces in the GUI as *"Failed to load pipeline"* because `run.py` calls `fix_console_encoding()` at module level and the exception is caught by the pipeline import guard.
+
 ## Test Suite
 
 `test_suite.py` uses a custom harness (no pytest/unittest dependency). Structure:
diff --git a/arma_modlist_tools/compat.py b/arma_modlist_tools/compat.py
index 5aadb93..f7b8499 100644
--- a/arma_modlist_tools/compat.py
+++ b/arma_modlist_tools/compat.py
@@ -102,6 +102,8 @@ def fix_console_encoding() -> None:
     """
     if not is_windows():
         return
+    if sys.stdout is None or sys.stderr is None:
+        return
     if sys.stdout.encoding and sys.stdout.encoding.lower() == "utf-8":
         return
     sys.stdout = io.TextIOWrapper(sys.stdout.buffer, encoding="utf-8", errors="replace")
diff --git a/test_suite.py b/test_suite.py
index dedea7c..b387397 100644
--- a/test_suite.py
+++ b/test_suite.py
@@ -2076,8 +2076,21 @@ test("compat: _read_os_release parses key=value pairs",                  _test_r
 test("compat: _read_os_release returns {} when file missing",            _test_read_os_release_handles_missing_file)
 test("compat: _is_headless returns False when DISPLAY is set",           _test_is_headless_with_display)
 test("compat: _is_headless returns True when no display env vars",       _test_is_headless_without_display)
+def _test_fix_console_encoding_none_stdout():
+    """fix_console_encoding is a no-op when sys.stdout is None (pythonw.exe)."""
+    original_stdout = sys.stdout
+    try:
+        with _patch("arma_modlist_tools.compat.is_windows", return_value=True):
+            sys.stdout = None
+            _compat_mod.fix_console_encoding()  # must not raise
+            assert sys.stdout is None
+    finally:
+        sys.stdout = original_stdout
+
+
 test("compat: fix_console_encoding is no-op on non-Windows",             _test_fix_console_encoding_non_windows_noop)
 test("compat: fix_console_encoding skips when stdout already UTF-8",     _test_fix_console_encoding_already_utf8)
+test("compat: fix_console_encoding is no-op when stdout is None",        _test_fix_console_encoding_none_stdout)
 
 
 # ---------------------------------------------------------------------------