diff --git a/Modules/_io/bufferedio.c b/Modules/_io/bufferedio.c
index 63ae1cb..cdaa36e 100644
--- a/Modules/_io/bufferedio.c
+++ b/Modules/_io/bufferedio.c
@@ -589,7 +589,7 @@
 static void
 _bufferedwriter_reset_buf(buffered *self);
 static PyObject *
-_bufferedreader_peek_unlocked(buffered *self, Py_ssize_t);
+_bufferedreader_peek_unlocked(buffered *self);
 static PyObject *
 _bufferedreader_read_all(buffered *self);
 static PyObject *
@@ -797,7 +797,7 @@
             goto end;
         Py_CLEAR(res);
     }
-    res = _bufferedreader_peek_unlocked(self, n);
+    res = _bufferedreader_peek_unlocked(self);
 
 end:
     LEAVE_BUFFERED(self)
@@ -1611,7 +1611,7 @@
 }
 
 static PyObject *
-_bufferedreader_peek_unlocked(buffered *self, Py_ssize_t n)
+_bufferedreader_peek_unlocked(buffered *self)
 {
     Py_ssize_t have, r;