diff --git a/Misc/NEWS b/Misc/NEWS
index 713e422..6c51aa6 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -24,6 +24,9 @@
 Library
 -------
 
+- Issue #9448: Fix a leak of OS resources (mutexes or semaphores) when
+  re-initializing a buffered IO object by calling its ``__init__`` method.
+
 - Issue #8471: In doctest, properly reset the output stream to an empty
   string when Unicode was previously output.
 
diff --git a/Modules/_io/bufferedio.c b/Modules/_io/bufferedio.c
index feee9be..9a14d26 100644
--- a/Modules/_io/bufferedio.c
+++ b/Modules/_io/bufferedio.c
@@ -636,6 +636,8 @@
         return -1;
     }
 #ifdef WITH_THREAD
+    if (self->lock)
+        PyThread_free_lock(self->lock);
     self->lock = PyThread_allocate_lock();
     if (self->lock == NULL) {
         PyErr_SetString(PyExc_RuntimeError, "can't allocate read lock");