diff --git a/src/trio/_subprocess.py b/src/trio/_subprocess.py
index 710600dcf4..b384d18ffa 100644
--- a/src/trio/_subprocess.py
+++ b/src/trio/_subprocess.py
@@ -50,8 +50,6 @@
 
     def pidfd_open(fd: int, flags: int) -> int: ...
 
-    from ._subprocess_platform import ClosableReceiveStream, ClosableSendStream
-
 else:
     can_try_pidfd_open = True
     try:
@@ -171,9 +169,9 @@ def __init__(
         if self.stdin is not None and self.stdout is not None:
             self.stdio = StapledStream(self.stdin, self.stdout)
 
-        self._wait_lock: Lock = Lock()
+        self._wait_lock = Lock()
 
-        self._pidfd: FileIO | None = None
+        self._pidfd = None
         if can_try_pidfd_open:
             try:
                 fd: int = pidfd_open(self._proc.pid, 0)
@@ -188,6 +186,8 @@ def __init__(
                 # make sure it'll get closed.
                 self._pidfd = FileIO(fd)
 
+        # TODO: remove the following two type hints, required only due to
+        # https://github.com/microsoft/pyright/issues/11917
         self.args: StrOrBytesPath | Sequence[StrOrBytesPath] = self._proc.args
         self.pid: int = self._proc.pid
 
@@ -381,9 +381,9 @@ async def _open_process(
                 "shell=True on UNIX systems",
             )
 
-    trio_stdin: ClosableSendStream | None = None
-    trio_stdout: ClosableReceiveStream | None = None
-    trio_stderr: ClosableReceiveStream | None = None
+    trio_stdin = None
+    trio_stdout = None
+    trio_stderr = None
     # Close the parent's handle for each child side of a pipe; we want the child to
     # have the only copy, so that when it exits we can read EOF on our side. The
     # trio ends of pipes will be transferred to the Process object, which will be
diff --git a/src/trio/_tests/type_tests/subprocesses.py b/src/trio/_tests/type_tests/subprocesses.py
index de3b5e8906..689ffd7d95 100644
--- a/src/trio/_tests/type_tests/subprocesses.py
+++ b/src/trio/_tests/type_tests/subprocesses.py
@@ -1,6 +1,12 @@
+import os
 import sys
+from collections.abc import Sequence
+from typing import TypeAlias
 
 import trio
+from typing_extensions import assert_type
+
+StrOrBytesPath: TypeAlias = str | bytes | os.PathLike[str] | os.PathLike[bytes]
 
 
 async def test() -> None:
@@ -21,3 +27,15 @@ async def test() -> None:
         # 3.11+:
         await trio.run_process("python", process_group=5)  # type: ignore
         await trio.lowlevel.open_process("python", process_group=5)  # type: ignore
+
+
+def check_processes(proc: trio.Process) -> None:
+    assert_type(proc.stdin, trio.abc.SendStream | None)
+    assert_type(proc.stdout, trio.abc.ReceiveStream | None)
+    assert_type(proc.stderr, trio.abc.ReceiveStream | None)
+    assert_type(
+        proc.stdio,
+        trio.StapledStream[trio.abc.SendStream, trio.abc.ReceiveStream] | None,
+    )
+    assert_type(proc.args, StrOrBytesPath | Sequence[StrOrBytesPath])
+    assert_type(proc.pid, int)