diff --git a/src/trio/_sync.py b/src/trio/_sync.py
index dbdee0798..d8c16f6d9 100644
--- a/src/trio/_sync.py
+++ b/src/trio/_sync.py
@@ -377,8 +377,8 @@ async def acquire_on_behalf_of(self, borrower: Task | object) -> None:
             self._pending_borrowers[task] = borrower
             try:
                 await self._lot.park()
-            except trio.Cancelled:
-                self._pending_borrowers.pop(task)
+            except BaseException:
+                self._pending_borrowers.pop(task, None)
                 raise
         else:
             await trio.lowlevel.cancel_shielded_checkpoint()