diff --git a/src/screener/__main__.py b/src/screener/__main__.py
index 12c3e28..fd8820e 100644
--- a/src/screener/__main__.py
+++ b/src/screener/__main__.py
@@ -1,63 +1,7 @@
-import sys
-from argparse import ArgumentParser
-from pathlib import Path
-
-from screener.checker import Checker
-from screener.parser import parse_epub, parse_kindle
-from screener.reader import EpubFileReader, KindleFileReader
-
-
-def init_argparse() -> ArgumentParser:
-    parser = ArgumentParser(
-        prog="screener",
-        usage="%(prog)s [OPTION] [FILE]...",
-        description="Check e-book files for security and privacy issues.",
-    )
-    parser.add_argument(
-        "-v",
-        "--version",
-        action="version",
-        version=f"{parser.prog} version 0.5.0",
-    )
-    parser.add_argument("files", nargs="*")
-    return parser
-
-
-def check_file(file: Path) -> Checker:
-    checker = Checker(file)
-    match extension := file.suffix:
-        case ".epub":
-            with EpubFileReader(file) as epub:
-                parse_epub(checker, epub.file_path)
-        case ".azw3" | ".mobi":
-            with KindleFileReader(file) as azw3:
-                parse_kindle(checker, azw3.file_path)
-        case _:
-            msg = f"unsupported file extension: {extension}"
-            raise ValueError(msg)
-    return checker
-
-
-def main() -> None:
-    parser = init_argparse()
-    args = parser.parse_args()
-    if not args.files:
-        print("No files specified. Run with -h for help.", file=sys.stderr)
-    exit_code = 0
-    for file in args.files:
-        if file == "-":
-            print("stdin not supported", file=sys.stderr)
-            continue
-        checker = check_file(Path(file))
-        if checker.diagnostics:
-            exit_code = 1
-            for diagnostic in checker.diagnostics:
-                print(diagnostic)
-        else:
-            print(f"{checker.file_path.name} is safe")
-
-    sys.exit(exit_code)
-
-
-if __name__ == "__main__":
-    main()
+from __future__ import annotations
+
+import sys
+
+from screener.cli import main
+
+sys.exit(main())
diff --git a/src/screener/cli.py b/src/screener/cli.py
new file mode 100644
index 0000000..165c1c0
--- /dev/null
+++ b/src/screener/cli.py
@@ -0,0 +1,60 @@
+from __future__ import annotations
+
+import sys
+from argparse import ArgumentParser
+from pathlib import Path
+from typing import TYPE_CHECKING
+
+from screener.checker import Checker
+from screener.parser import parse_epub, parse_kindle
+from screener.reader import EpubFileReader, KindleFileReader
+
+if TYPE_CHECKING:
+    from collections.abc import Sequence
+
+
+def check_file(file: Path) -> Checker:
+    checker = Checker(file)
+    match extension := file.suffix:
+        case ".epub":
+            with EpubFileReader(file) as epub:
+                parse_epub(checker, epub.file_path)
+        case ".azw3" | ".mobi":
+            with KindleFileReader(file) as azw3:
+                parse_kindle(checker, azw3.file_path)
+        case _:
+            msg = f"unsupported file extension: {extension}"
+            raise ValueError(msg)
+    return checker
+
+
+def main(argv: Sequence[str] | None = None) -> int:
+    parser = ArgumentParser(
+        prog="screener",
+        usage="%(prog)s [OPTION] [FILE]...",
+        description="Check e-book files for security and privacy issues.",
+    )
+    parser.add_argument(
+        "-v",
+        "--version",
+        action="version",
+        version=f"{parser.prog} version 0.5.0",
+    )
+    parser.add_argument("files", nargs="*")
+    args = parser.parse_args(argv)
+    if not args.files:
+        print("No files specified. Run with -h for help.", file=sys.stderr)
+    exit_code = 0
+    for file in args.files:
+        if file == "-":
+            print("stdin not supported", file=sys.stderr)
+            continue
+        checker = check_file(Path(file))
+        if checker.diagnostics:
+            exit_code = 1
+            for diagnostic in checker.diagnostics:
+                print(diagnostic)
+        else:
+            print(f"{checker.file_path.name} is safe")
+
+    return exit_code