diff --git a/mercurial/utils/procutil.py b/mercurial/utils/procutil.py
--- a/mercurial/utils/procutil.py
+++ b/mercurial/utils/procutil.py
@@ -75,7 +75,9 @@
         return res
 
 
+# pytype: disable=attribute-error
 io.BufferedIOBase.register(LineBufferedWrapper)
+# pytype: enable=attribute-error
 
 
 def make_line_buffered(stream):
@@ -114,7 +116,9 @@
         return total_written
 
 
+# pytype: disable=attribute-error
 io.IOBase.register(WriteAllWrapper)
+# pytype: enable=attribute-error
 
 
 def _make_write_all(stream):
@@ -767,6 +771,7 @@
             raise
         finally:
             if stdin_bytes is not None:
+                assert not isinstance(stdin, int)
                 stdin.close()
         if not ensurestart:
             # Even though we're not waiting on the child process,
diff --git a/tests/test-check-pytype.t b/tests/test-check-pytype.t
--- a/tests/test-check-pytype.t
+++ b/tests/test-check-pytype.t
@@ -32,7 +32,6 @@
 mercurial/testing/storage.py  # tons of [attribute-error]
 mercurial/ui.py               # [attribute-error], [wrong-arg-types]
 mercurial/unionrepo.py        # ui, svfs, unfiltered [attribute-error]
-mercurial/utils/procutil.py   # [attribute-error], [module-attr], [bad-return-type]
 mercurial/utils/memorytop.py  # not 3.6 compatible
 mercurial/win32.py            # [not-callable]
 mercurial/wireprotoframing.py # [unsupported-operands], [attribute-error], [import-error]
@@ -68,7 +67,6 @@
   >    -x mercurial/thirdparty \
   >    -x mercurial/ui.py \
   >    -x mercurial/unionrepo.py \
-  >    -x mercurial/utils/procutil.py \
   >    -x mercurial/utils/memorytop.py \
   >    -x mercurial/win32.py \
   >    -x mercurial/wireprotoframing.py \