diff --git a/Modules/_io/_iomodule.c b/Modules/_io/_iomodule.c
index ee4eca70e2af8f..2457cb124036fe 100644
--- a/Modules/_io/_iomodule.c
+++ b/Modules/_io/_iomodule.c
@@ -582,6 +582,7 @@ iomodule_traverse(PyObject *mod, visitproc visit, void *arg) {
         return 0;
     Py_VISIT(state->unsupported_operation);
 
+    Py_VISIT(state->PyIOBase_Type);
     Py_VISIT(state->PyIncrementalNewlineDecoder_Type);
     Py_VISIT(state->PyRawIOBase_Type);
     Py_VISIT(state->PyBufferedIOBase_Type);
@@ -609,6 +610,7 @@ iomodule_clear(PyObject *mod) {
         return 0;
     Py_CLEAR(state->unsupported_operation);
 
+    Py_CLEAR(state->PyIOBase_Type);
     Py_CLEAR(state->PyIncrementalNewlineDecoder_Type);
     Py_CLEAR(state->PyRawIOBase_Type);
     Py_CLEAR(state->PyBufferedIOBase_Type);
@@ -751,6 +753,7 @@ PyInit__io(void)
     }
 
     // Base classes
+    state->PyIOBase_Type = (PyTypeObject *)Py_NewRef(&PyIOBase_Type);
     ADD_TYPE(m, state->PyIncrementalNewlineDecoder_Type, &nldecoder_spec, NULL);
     ADD_TYPE(m, state->PyBytesIOBuffer_Type, &bytesiobuf_spec, NULL);
 
diff --git a/Modules/_io/_iomodule.h b/Modules/_io/_iomodule.h
index 44d651338e6975..ae06fecc48b450 100644
--- a/Modules/_io/_iomodule.h
+++ b/Modules/_io/_iomodule.h
@@ -149,6 +149,7 @@ struct _io_state {
     PyObject *unsupported_operation;
 
     /* Types */
+    PyTypeObject *PyIOBase_Type;
     PyTypeObject *PyIncrementalNewlineDecoder_Type;
     PyTypeObject *PyRawIOBase_Type;
     PyTypeObject *PyBufferedIOBase_Type;
diff --git a/Modules/_io/clinic/iobase.c.h b/Modules/_io/clinic/iobase.c.h
index 727398800bec01..7e6b3b5b78e8f6 100644
--- a/Modules/_io/clinic/iobase.c.h
+++ b/Modules/_io/clinic/iobase.c.h
@@ -231,20 +231,24 @@ PyDoc_STRVAR(_io__IOBase_fileno__doc__,
 "fileno($self, /)\n"
 "--\n"
 "\n"
-"Returns underlying file descriptor if one exists.\n"
+"Return underlying file descriptor if one exists.\n"
 "\n"
-"OSError is raised if the IO object does not use a file descriptor.");
+"Raise OSError if the IO object does not use a file descriptor.");
 
 #define _IO__IOBASE_FILENO_METHODDEF    \
-    {"fileno", (PyCFunction)_io__IOBase_fileno, METH_NOARGS, _io__IOBase_fileno__doc__},
+    {"fileno", _PyCFunction_CAST(_io__IOBase_fileno), METH_METHOD|METH_FASTCALL|METH_KEYWORDS, _io__IOBase_fileno__doc__},
 
 static PyObject *
-_io__IOBase_fileno_impl(PyObject *self);
+_io__IOBase_fileno_impl(PyObject *self, PyTypeObject *cls);
 
 static PyObject *
-_io__IOBase_fileno(PyObject *self, PyObject *Py_UNUSED(ignored))
+_io__IOBase_fileno(PyObject *self, PyTypeObject *cls, PyObject *const *args, Py_ssize_t nargs, PyObject *kwnames)
 {
-    return _io__IOBase_fileno_impl(self);
+    if (nargs) {
+        PyErr_SetString(PyExc_TypeError, "fileno() takes no arguments");
+        return NULL;
+    }
+    return _io__IOBase_fileno_impl(self, cls);
 }
 
 PyDoc_STRVAR(_io__IOBase_isatty__doc__,
@@ -416,4 +420,4 @@ _io__RawIOBase_readall(PyObject *self, PyObject *Py_UNUSED(ignored))
 {
     return _io__RawIOBase_readall_impl(self);
 }
-/*[clinic end generated code: output=b6d4845254da1da2 input=a9049054013a1b77]*/
+/*[clinic end generated code: output=63bc25a5bfcecaf0 input=a9049054013a1b77]*/
diff --git a/Modules/_io/iobase.c b/Modules/_io/iobase.c
index a74e46cc8dc536..26f2a3155bda62 100644
--- a/Modules/_io/iobase.c
+++ b/Modules/_io/iobase.c
@@ -511,15 +511,17 @@ iobase_exit(PyObject *self, PyObject *args)
 
 /*[clinic input]
 _io._IOBase.fileno
+    cls: defining_class
+    /
 
-Returns underlying file descriptor if one exists.
+Return underlying file descriptor if one exists.
 
-OSError is raised if the IO object does not use a file descriptor.
+Raise OSError if the IO object does not use a file descriptor.
 [clinic start generated code]*/
 
 static PyObject *
-_io__IOBase_fileno_impl(PyObject *self)
-/*[clinic end generated code: output=7cc0973f0f5f3b73 input=4e37028947dc1cc8]*/
+_io__IOBase_fileno_impl(PyObject *self, PyTypeObject *cls)
+/*[clinic end generated code: output=7caaa32a6f4ada3d input=1927c8bea5c85099]*/
 {
     _PyIO_State *state = IO_STATE();
     return iobase_unsupported(state, "fileno");