diff --git a/std/stdio.d b/std/stdio.d
index 1e1485d07..b9a801041 100644
--- a/std/stdio.d
+++ b/std/stdio.d
@@ -1682,13 +1682,14 @@ must copy the previous contents if you wish to retain them.
 
 Params:
 buf = Buffer used to store the resulting line data. buf is
-resized as necessary.
+enlarged if necessary, then set to the slice exactly containing the line.
 terminator = Line terminator (by default, `'\n'`). Use
 $(REF newline, std,ascii) for portability (unless the file was opened in
 text mode).
 
 Returns:
-0 for end of file, otherwise number of characters read
+0 for end of file, otherwise number of characters read.
+The return value will always be equal to `buf.length`.
 
 Throws: `StdioException` on I/O error, or `UnicodeException` on Unicode
 conversion error.