diff --git a/httpcore/_async/http2.py b/httpcore/_async/http2.py
index dbd0beeb..50738f2e 100644
--- a/httpcore/_async/http2.py
+++ b/httpcore/_async/http2.py
@@ -408,8 +408,8 @@ async def _receive_remote_settings_change(
 
     async def _response_closed(self, stream_id: int) -> None:
         await self._max_streams_semaphore.release()
-        del self._events[stream_id]
         async with self._state_lock:
+            del self._events[stream_id]
             if self._connection_terminated and not self._events:
                 await self.aclose()
 
diff --git a/httpcore/_sync/http2.py b/httpcore/_sync/http2.py
index ddcc1890..6dcb10b0 100644
--- a/httpcore/_sync/http2.py
+++ b/httpcore/_sync/http2.py
@@ -408,8 +408,8 @@ def _receive_remote_settings_change(
 
     def _response_closed(self, stream_id: int) -> None:
         self._max_streams_semaphore.release()
-        del self._events[stream_id]
         with self._state_lock:
+            del self._events[stream_id]
             if self._connection_terminated and not self._events:
                 self.close()