diff --git a/platformio/compat.py b/platformio/compat.py
index 694783c2..008dc7ae 100644
--- a/platformio/compat.py
+++ b/platformio/compat.py
@@ -30,6 +30,20 @@ else:
     from asyncio import get_event_loop as aio_get_running_loop
 
 
+if sys.version_info >= (3, 8):
+    from shlex import join as shlex_join
+else:
+
+    def shlex_join(split_command):
+        return " ".join(shlex.quote(arg) for arg in split_command)
+
+
+if sys.version_info >= (3, 9):
+    from asyncio import to_thread as aio_to_thread
+else:
+    from starlette.concurrency import run_in_threadpool as aio_to_thread
+
+
 PY2 = sys.version_info[0] == 2  # DO NOT REMOVE IT. ESP8266/ESP32 depend on it
 IS_CYGWIN = sys.platform.startswith("cygwin")
 IS_WINDOWS = WINDOWS = sys.platform.startswith("win")
@@ -37,13 +51,6 @@ IS_MACOS = sys.platform.startswith("darwin")
 MISSING = object()
 string_types = (str,)
 
-try:
-    from shlex import join as shlex_join
-except ImportError:
-
-    def shlex_join(split_command):
-        return " ".join(shlex.quote(arg) for arg in split_command)
-
 
 def is_bytes(x):
     return isinstance(x, (bytes, memoryview, bytearray))
diff --git a/platformio/home/rpc/handlers/os.py b/platformio/home/rpc/handlers/os.py
index 0d6b9f48..dd651193 100644
--- a/platformio/home/rpc/handlers/os.py
+++ b/platformio/home/rpc/handlers/os.py
@@ -19,10 +19,10 @@ import shutil
 from functools import cmp_to_key
 
 import click
-from starlette.concurrency import run_in_threadpool
 
 from platformio import fs
 from platformio.cache import ContentCache
+from platformio.compat import aio_to_thread
 from platformio.device.list.util import list_logical_devices
 from platformio.home.rpc.handlers.base import BaseRPCHandler
 from platformio.http import HTTPSession, ensure_internet_on
@@ -33,7 +33,7 @@ class HTTPAsyncSession(HTTPSession):
         self, *args, **kwargs
     ):
         func = super().request
-        return await run_in_threadpool(func, *args, **kwargs)
+        return await aio_to_thread(func, *args, **kwargs)
 
 
 class OSRPC(BaseRPCHandler):
diff --git a/platformio/home/rpc/handlers/piocore.py b/platformio/home/rpc/handlers/piocore.py
index 080ba96c..b09338e5 100644
--- a/platformio/home/rpc/handlers/piocore.py
+++ b/platformio/home/rpc/handlers/piocore.py
@@ -22,13 +22,13 @@ import threading
 
 import click
 from ajsonrpc.core import JSONRPC20DispatchException
-from starlette.concurrency import run_in_threadpool
 
 from platformio import __main__, __version__, app, fs, proc, util
 from platformio.compat import (
     IS_WINDOWS,
     aio_create_task,
     aio_get_running_loop,
+    aio_to_thread,
     get_locale_encoding,
     is_bytes,
 )
@@ -177,7 +177,7 @@ class PIOCoreRPC(BaseRPCHandler):
 
     @staticmethod
     async def _call_subprocess(args, options):
-        result = await run_in_threadpool(
+        result = await aio_to_thread(
             proc.exec_command,
             [get_core_fullpath()] + args,
             cwd=options.get("cwd") or os.getcwd(),
@@ -197,7 +197,7 @@ class PIOCoreRPC(BaseRPCHandler):
                 exit_code,
             )
 
-        return await run_in_threadpool(
+        return await aio_to_thread(
             _thread_safe_call, args=args, cwd=options.get("cwd") or os.getcwd()
         )
 
diff --git a/platformio/home/rpc/handlers/registry.py b/platformio/home/rpc/handlers/registry.py
index 1370f328..84a374b6 100644
--- a/platformio/home/rpc/handlers/registry.py
+++ b/platformio/home/rpc/handlers/registry.py
@@ -13,8 +13,8 @@
 # limitations under the License.
 
 from ajsonrpc.core import JSONRPC20DispatchException
-from starlette.concurrency import run_in_threadpool
 
+from platformio.compat import aio_to_thread
 from platformio.home.rpc.handlers.base import BaseRPCHandler
 from platformio.registry.client import RegistryClient
 
@@ -24,7 +24,7 @@ class RegistryRPC(BaseRPCHandler):
     async def call_client(method, *args, **kwargs):
         try:
             client = RegistryClient()
-            return await run_in_threadpool(getattr(client, method), *args, **kwargs)
+            return await aio_to_thread(getattr(client, method), *args, **kwargs)
         except Exception as exc:  # pylint: disable=bare-except
             raise JSONRPC20DispatchException(
                 code=5000, message="Registry Call Error", data=str(exc)