diff --git a/docs/cli-reference/base-options.md b/docs/cli-reference/base-options.md
index 532a6cd0c..3087801b4 100644
--- a/docs/cli-reference/base-options.md
+++ b/docs/cli-reference/base-options.md
@@ -19,7 +19,9 @@ Specify character encoding for input and output files.
 The `--encoding` flag sets the character encoding used when reading
 the schema file and writing the generated Python code. This is useful
 for schemas containing non-ASCII characters (e.g., Japanese, Chinese).
-Default is utf-8.
+Default is the system's preferred encoding (via `locale.getpreferredencoding()`),
+which is typically UTF-8 on Linux/macOS but may differ on Windows (e.g., cp1252).
+For consistent cross-platform behavior, explicitly specify `--encoding utf-8`.
 
 !!! tip "Usage"
 
diff --git a/tests/test_main_kr.py b/tests/test_main_kr.py
index d0efb0a38..a1bdb986e 100644
--- a/tests/test_main_kr.py
+++ b/tests/test_main_kr.py
@@ -1284,7 +1284,9 @@ def test_encoding_option(output_file: Path) -> None:
     The `--encoding` flag sets the character encoding used when reading
     the schema file and writing the generated Python code. This is useful
     for schemas containing non-ASCII characters (e.g., Japanese, Chinese).
-    Default is utf-8.
+    Default is the system's preferred encoding (via `locale.getpreferredencoding()`),
+    which is typically UTF-8 on Linux/macOS but may differ on Windows (e.g., cp1252).
+    For consistent cross-platform behavior, explicitly specify `--encoding utf-8`.
     """
     run_main_and_assert(
         input_path=JSON_SCHEMA_DATA_PATH / "encoding_test.json",