diff --git a/Doc/lib/libcsv.tex b/Doc/lib/libcsv.tex
index 9cf5044c64f..24b063e776d 100644
--- a/Doc/lib/libcsv.tex
+++ b/Doc/lib/libcsv.tex
@@ -312,7 +312,7 @@ The ``Hello, world'' of csv reading is
 
 \begin{verbatim}
 import csv
-reader = csv.reader(file("some.csv"))
+reader = csv.reader(file("some.csv", "rb"))
 for row in reader:
     print row
 \end{verbatim}
@@ -321,7 +321,7 @@ The corresponding simplest possible writing example is
 
 \begin{verbatim}
 import csv
-writer = csv.writer(file("some.csv", "w"))
+writer = csv.writer(file("some.csv", "wb"))
 for row in someiterable:
     writer.writerow(row)
 \end{verbatim}