diff --git a/Doc/whatsnew/whatsnew25.tex b/Doc/whatsnew/whatsnew25.tex
index 85d5a2a5fad..b2f73804e4c 100644
--- a/Doc/whatsnew/whatsnew25.tex
+++ b/Doc/whatsnew/whatsnew25.tex
@@ -1294,6 +1294,17 @@ the function is 6 times faster.
 (Contributed by Alan McIntyre and committed at the NeedForSpeed sprint.)
 % Patch 1442927
 
+\item It's now illegal to mix iterating over a file 
+with \code{for line in \var{file}} and calling 
+the file object's \method{read()}/\method{readline()}/\method{readlines()}
+methods.  Iteration uses an internal buffer and the 
+\method{read*()} methods don't use that buffer.  
+Instead they would return the data following the buffer, causing the
+data to appear out of order.  Mixing iteration and these methods will
+now trigger a \exception{ValueError} from the \method{read*()} method.
+(Implemented by Thomas Wouters.)
+% Patch 1397960
+
 \item The \module{struct} module now compiles structure format 
 strings into an internal representation and caches this
 representation, yielding a 20\% speedup.  (Contributed by Bob Ippolito