diff --git a/src/ocrmypdf/_pipeline.py b/src/ocrmypdf/_pipeline.py
index 609e1e72..36105fb7 100644
--- a/src/ocrmypdf/_pipeline.py
+++ b/src/ocrmypdf/_pipeline.py
@@ -23,7 +23,7 @@ from contextlib import suppress
 from datetime import datetime, timezone
 from pathlib import Path
 from shutil import copyfileobj
-from typing import Dict, Iterable, Optional
+from typing import BinaryIO, Dict, Iterable, Optional, Union, cast
 
 import img2pdf
 import pikepdf
@@ -817,16 +817,17 @@ def merge_sidecars(txt_files: Iterable[Optional[Path]], context: PdfContext):
     return output_file
 
 
-def copy_final(input_file: Path, output_file: Path, _context: PdfContext):
+def copy_final(input_file, output_file, _context: PdfContext):
     log.debug('%s -> %s', input_file, output_file)
     with open(input_file, 'rb') as input_stream:
         if output_file == '-':
             copyfileobj(input_stream, sys.stdout.buffer)
             sys.stdout.flush()
         elif hasattr(output_file, 'writable'):
-            copyfileobj(input_stream, output_file)
+            output_stream = output_file
+            copyfileobj(input_stream, output_stream)
             with suppress(AttributeError):
-                output_file.flush()
+                output_stream.flush()
         else:
             # At this point we overwrite the output_file specified by the user
             # use copyfileobj because then we use open() to create the file and
diff --git a/src/ocrmypdf/_validation.py b/src/ocrmypdf/_validation.py
index de7ba97c..f64ed497 100644
--- a/src/ocrmypdf/_validation.py
+++ b/src/ocrmypdf/_validation.py
@@ -342,7 +342,7 @@ def create_input_file(options, work_folder: Path) -> Tuple[Path, str]:
         if not options.input_file.readable():
             raise InputFileError("Input file stream is not readable")
         log.info('reading file from input stream')
-        target = os.path.join(work_folder, 'stream')
+        target = work_folder / 'stream'
         with open(target, 'wb') as stream_buffer:
             copyfileobj(options.input_file, stream_buffer)
         return target, "stream"
diff --git a/src/ocrmypdf/pdfinfo/info.py b/src/ocrmypdf/pdfinfo/info.py
index 1800f1e4..b9aad6d3 100644
--- a/src/ocrmypdf/pdfinfo/info.py
+++ b/src/ocrmypdf/pdfinfo/info.py
@@ -25,6 +25,7 @@ from functools import partial
 from math import hypot, isclose
 from os import PathLike
 from pathlib import Path
+from typing import Any, Dict, List
 from warnings import warn
 
 import pikepdf
@@ -568,7 +569,7 @@ def simplify_textboxes(miner, textbox_getter):
 def _pdf_get_pageinfo(
     pdf, pageno: int, infile: PathLike, check_pages, detailed_analysis
 ):
-    pageinfo = {}
+    pageinfo: Dict[str, Any] = {}
     pageinfo['pageno'] = pageno
     pageinfo['images'] = []