diff --git a/Modules/_io/bufferedio.c b/Modules/_io/bufferedio.c
index 625a61e..6d67751 100644
--- a/Modules/_io/bufferedio.c
+++ b/Modules/_io/bufferedio.c
@@ -190,8 +190,8 @@
 PyDoc_STRVAR(bufferediobase_write_doc,
     "Write the given buffer to the IO stream.\n"
     "\n"
-    "Returns the number of bytes written, which is never less than\n"
-    "len(b).\n"
+    "Returns the number of bytes written, which is always the length of b\n"
+    "in bytes.\n"
     "\n"
     "Raises BlockingIOError if the buffer is full and the\n"
     "underlying raw stream cannot accept more data at the moment.\n");
diff --git a/Modules/_io/bytesio.c b/Modules/_io/bytesio.c
index 058df47..9e5d78b 100644
--- a/Modules/_io/bytesio.c
+++ b/Modules/_io/bytesio.c
@@ -548,7 +548,7 @@
     buffer: Py_buffer(accept={rwbuffer})
     /
 
-Read up to len(buffer) bytes into buffer.
+Read bytes into buffer.
 
 Returns number of bytes read (0 for EOF), or None if the object
 is set not to block and has no data to read.
@@ -556,7 +556,7 @@
 
 static PyObject *
 _io_BytesIO_readinto_impl(bytesio *self, Py_buffer *buffer)
-/*[clinic end generated code: output=a5d407217dcf0639 input=b52a8782706f0037]*/
+/*[clinic end generated code: output=a5d407217dcf0639 input=1424d0fdce857919]*/
 {
     Py_ssize_t len, n;
 
diff --git a/Modules/_io/clinic/bytesio.c.h b/Modules/_io/clinic/bytesio.c.h
index e468215..5f2abb0 100644
--- a/Modules/_io/clinic/bytesio.c.h
+++ b/Modules/_io/clinic/bytesio.c.h
@@ -259,7 +259,7 @@
 "readinto($self, buffer, /)\n"
 "--\n"
 "\n"
-"Read up to len(buffer) bytes into buffer.\n"
+"Read bytes into buffer.\n"
 "\n"
 "Returns number of bytes read (0 for EOF), or None if the object\n"
 "is set not to block and has no data to read.");
@@ -419,4 +419,4 @@
 exit:
     return return_value;
 }
-/*[clinic end generated code: output=164cf0e4117dadbe input=a9049054013a1b77]*/
+/*[clinic end generated code: output=60ce2c6272718431 input=a9049054013a1b77]*/
diff --git a/Modules/_io/clinic/fileio.c.h b/Modules/_io/clinic/fileio.c.h
index 4a1205e..1042008 100644
--- a/Modules/_io/clinic/fileio.c.h
+++ b/Modules/_io/clinic/fileio.c.h
@@ -222,7 +222,7 @@
 "write($self, b, /)\n"
 "--\n"
 "\n"
-"Write bytes b to file, return number written.\n"
+"Write buffer b to file, return number of bytes written.\n"
 "\n"
 "Only makes one system call, so not all of the data may be written.\n"
 "The number of bytes actually written is returned.  In non-blocking mode,\n"
@@ -364,4 +364,4 @@
 #ifndef _IO_FILEIO_TRUNCATE_METHODDEF
     #define _IO_FILEIO_TRUNCATE_METHODDEF
 #endif /* !defined(_IO_FILEIO_TRUNCATE_METHODDEF) */
-/*[clinic end generated code: output=b1a20b10c81add64 input=a9049054013a1b77]*/
+/*[clinic end generated code: output=dcbc39b466598492 input=a9049054013a1b77]*/
diff --git a/Modules/_io/fileio.c b/Modules/_io/fileio.c
index dbd604a..83b6a32 100644
--- a/Modules/_io/fileio.c
+++ b/Modules/_io/fileio.c
@@ -836,7 +836,7 @@
     b: Py_buffer
     /
 
-Write bytes b to file, return number written.
+Write buffer b to file, return number of bytes written.
 
 Only makes one system call, so not all of the data may be written.
 The number of bytes actually written is returned.  In non-blocking mode,
@@ -845,7 +845,7 @@
 
 static PyObject *
 _io_FileIO_write_impl(fileio *self, Py_buffer *b)
-/*[clinic end generated code: output=b4059db3d363a2f7 input=ffbd8834f447ac31]*/
+/*[clinic end generated code: output=b4059db3d363a2f7 input=6e7908b36f0ce74f]*/
 {
     Py_ssize_t n;
     int err;
diff --git a/Modules/_io/iobase.c b/Modules/_io/iobase.c
index 090891d..212b0dd 100644
--- a/Modules/_io/iobase.c
+++ b/Modules/_io/iobase.c
@@ -53,8 +53,9 @@
     "called.\n"
     "\n"
     "The basic type used for binary data read from or written to a file is\n"
-    "bytes. bytearrays are accepted too, and in some cases (such as\n"
-    "readinto) needed. Text I/O classes work with str data.\n"
+    "bytes. Other bytes-like objects are accepted as method arguments too.\n"
+    "In some cases (such as readinto), a writable object is required. Text\n"
+    "I/O classes work with str data.\n"
     "\n"
     "Note that calling any method (except additional calls to close(),\n"
     "which are ignored) on a closed stream should raise a ValueError.\n"