diff --git a/Modules/_io/bufferedio.c b/Modules/_io/bufferedio.c
--- a/Modules/_io/bufferedio.c
+++ b/Modules/_io/bufferedio.c
@@ -306,7 +306,14 @@ static int
         return 0;
     }
     Py_BEGIN_ALLOW_THREADS
-    PyThread_acquire_lock(self->lock, 1);
+    if (!_Py_Finalizing)
+        PyThread_acquire_lock(self->lock, 1);
+    else
+        /* When finalizing, we don't want a deadlock to happen with daemon
+         * threads abruptly shut down while they owned the lock.  Therefore,
+         * only wait for a grace period (1 s.).
+         */
+        PyThread_acquire_lock_timed(self->lock, 1e6, 0);
     Py_END_ALLOW_THREADS
     return 1;
 }