diff --git a/docs/versionhistory.rst b/docs/versionhistory.rst
index d4bec99d..ccaffa31 100644
--- a/docs/versionhistory.rst
+++ b/docs/versionhistory.rst
@@ -10,6 +10,11 @@ This library adheres to `Semantic Versioning 2.0 <http://semver.org/>`_.
   ``FileWriteStream``so they accept any path-like object (including the new asynchronous ``Path``
   class)
 - Dropped unnecessary dependency on the ``async_generator`` library
+- API changes:
+  * The following functions and methods are no longer asynchronous but can still be awaited on
+    (doing so will emit a deprecation warning):
+
+    * ``abc.BlockingPortal.stop``
 
 **3.2.1**
 
diff --git a/src/anyio/from_thread.py b/src/anyio/from_thread.py
index 26d4a262..a1cb0e95 100644
--- a/src/anyio/from_thread.py
+++ b/src/anyio/from_thread.py
@@ -9,6 +9,7 @@
 from warnings import warn
 
 from ._core import _eventloop
+from ._core._compat import DeprecatedAwaitable
 from ._core._eventloop import get_asynclib, get_cancelled_exc_class, threadlocals
 from ._core._synchronization import Event
 from ._core._tasks import CancelScope, create_task_group
@@ -130,7 +131,7 @@ async def __aenter__(self) -> 'BlockingPortal':
     async def __aexit__(self, exc_type: Optional[Type[BaseException]],
                         exc_val: Optional[BaseException],
                         exc_tb: Optional[TracebackType]) -> Optional[bool]:
-        await self.stop()
+        self.stop()
         return await self._task_group.__aexit__(exc_type, exc_val, exc_tb)
 
     def _check_running(self) -> None:
@@ -143,7 +144,7 @@ async def sleep_until_stopped(self) -> None:
         """Sleep until :meth:`stop` is called."""
         await self._stop_event.wait()
 
-    async def stop(self, cancel_remaining: bool = False) -> None:
+    def stop(self, cancel_remaining: bool = False) -> DeprecatedAwaitable:
         """
         Signal the portal to shut down.
 
@@ -154,11 +155,18 @@ async def stop(self, cancel_remaining: bool = False) -> None:
             finish before returning
 
         """
+        if self._event_loop_thread_id is None:
+            return
+        if threading.get_ident() != self._event_loop_thread_id:
+            raise RuntimeError('This method must be called from the event loop thread')
+
         self._event_loop_thread_id = None
         self._stop_event.set()
         if cancel_remaining:
             self._task_group.cancel_scope.cancel()
 
+        return DeprecatedAwaitable(self.stop)
+
     async def _call_func(self, func: Callable, args: tuple, kwargs: Dict[str, Any],
                          future: Future) -> None:
         def callback(f: Future) -> None: