diff --git a/Doc/library/struct.rst b/Doc/library/struct.rst
index 12d4fbc..7c38d1c 100644
--- a/Doc/library/struct.rst
+++ b/Doc/library/struct.rst
@@ -62,8 +62,8 @@ The module defines the following exception and functions:
 
    Unpack from the buffer *buffer* (presumably packed by ``pack(fmt, ...)``)
    according to the format string *fmt*.  The result is a tuple even if it
-   contains exactly one item.  The buffer must contain exactly the amount of
-   data required by the format (``len(bytes)`` must equal ``calcsize(fmt)``).
+   contains exactly one item.  The buffer must contain exactly as many bytes
+   as required by the format (``calcsize(fmt)``).
 
 
 .. function:: unpack_from(fmt, buffer, offset=0)